License Management

This page describes how to manage your QUBO++ license using the qbpp-license command-line utility. The license system is shared between QUBO++ (C++) and PyQBPP (Python).

License Types

QUBO++ offers several license types with different variable count limits and validity periods.

License Type	Key Required	Validity	CPU Variables	GPU Variables
Trial	Yes	30 days (renewable)	10,000	10,000
Other licenses	Yes	Set individually	Set individually	Set individually
Fallback	N/A	Always	100	100

The values in the table are limits on the total number of variables, counting both binary and native integer variables. 2,147,483,647 ($2^{31}-1$) equals the implementation capacity, which consists of $2^{30}$ binary variables and $2^{30}-1$ native integer variables.

Trial License: Free, self-service. Sign up at the QUBO++ User Portal using the sign-up code printed by qbpp-license -s. The Trial license is delivered via email on completion of registration.
Other licenses: Licenses with individually agreed validity periods and variable-count limits may be issued. The applicable terms are communicated when the license is issued.
Fallback Mode: When no valid license is set, the license is suspended, or the cache has expired with no network, QUBO++ runs with a 100-variable limit.

How variables are counted

The variable counts in the table are limits on the total of binary and native integer variables, counted as follows:

Binary variable: 1 each
Native integer variable: $\lceil \log_2 (r+1) \rceil$ each, where $r$ is its range (upper bound minus lower bound)

An integer variable is counted exactly as the binary-encoded integer variable (var_int) would consume, so the two representations are license-neutral.

The current usage is available via qbpp::used_var_count() (qbpp.used_var_count() in Python). Use it to check whether your model fits within the 10,000 of Trial or the 100 of Fallback.

What Unlimited means

When a license shows Unlimited for its variable counts, there is no license-side limit on the number of variables — the counted limits of Trial (10,000) and Fallback (100) do not apply.

The implementation capacity of QUBO++ still remains, however: binary variables and native integer variables can each be used up to $2^{30}-1$ = 1,073,741,823. Reaching this capacity raises an explicit capacity error, not a license error.

Obtaining a Trial License

Install QUBO++ on a Linux machine.
Run qbpp-license -s — your terminal prints today’s 8-character sign-up code along with the portal URL.
Open https://qubo-plus.github.io/portal/, fill the sign-up form, and enter the code from step 2.
After confirming your email, the portal displays your Trial license key (T-PREFIX-XXXXXX-XXXXXX-XXXXXX, where PREFIX is derived from your email local part).
Activate the key on your machine: qbpp-license -k T-... -a.

The 30-day Trial clock starts at the moment you sign up — the expiry date is fixed when the key is issued, so you can see your deadline in the portal immediately. Within the final week before expiry, the User Portal allows you to renew the Trial — the same license key is reused with the expiry pushed out by another 30 days, so your machine activations stay in place and no re-activation is needed.

Setting and Activating the License Key

Scope of this section: the activation flow described below — together with Checking License Status and Deactivating a License — applies to node-locked licenses (single-machine keys). Activation binds the key to a specific physical machine. For floating licenses, see Floating Licenses at the bottom of this page.

Virtual environments (Docker, VMs, ephemeral containers, etc.) are not supported with node-locked licenses. The machine fingerprint may not be stable, activation may fail, or the cached activation may be lost when the container is rebuilt — leaving the deactivation slot stranded on the server. If you need to run QUBO++ inside a virtual environment, use a floating license, which is designed for this case and works without any per-machine activation.

If you have a license key, set it using one of the following methods.

Method 1: Activate with `qbpp-license` (recommended)

Run the following command once per machine:

qbpp-license -k XXXXXX-XXXXXX-XXXXXX-XXXXXX -a

The license key is encrypted and cached locally. After activation, no environment variable or -k option is needed for subsequent runs — QUBO++ programs automatically use the cached key.

To re-activate or change the key, simply run the command again with a new key.

Method 2: Environment Variable

Set the QBPP_LICENSE_KEY environment variable to supply the key without writing it to the local cache — for example, to inject it from a deployment script or a CI secret:

export QBPP_LICENSE_KEY=XXXXXX-XXXXXX-XXXXXX-XXXXXX

Node-locked licenses are not recommended for Docker, VMs, or other ephemeral environments, even via this environment variable. Activation still binds to a machine fingerprint that is unstable in such environments, so a node-locked key cannot reliably run there. For Docker/VM/CI, use a floating license, which is not bound to a machine and reads the same QBPP_LICENSE_KEY variable.

Method 3: Embedding in Code

To bundle a license key inside an application, call license_key() in your code:

// C++
qbpp::license_key("XXXXXX-XXXXXX-XXXXXX-XXXXXX");

# Python
import pyqbpp as qbpp
qbpp.license_key("XXXXXX-XXXXXX-XXXXXX-XXXXXX")

A key set this way (the default form) is treated as an embedded default key with the lowest priority: it is used only on machines that have neither the environment variable nor an activated cached key. Users of your application can therefore switch to their own license simply by setting QBPP_LICENSE_KEY.

To force the key and override the environment variable and the cached key (the same treatment as qbpp-license -k), pass true as the second argument (force=True in Python):

qbpp::license_key("XXXXXX-XXXXXX-XXXXXX-XXXXXX", true);   // force

Priority

When multiple methods are used, the following priority applies:

-k argument or qbpp::license_key(key, true) in code (highest)
QBPP_LICENSE_KEY environment variable
Cached key
qbpp::license_key(key) in code (embedded default key, lowest)

Note: A Trial license key is required even for evaluation. Run qbpp-license -s to obtain a sign-up code, then register at the User Portal to receive your Trial key.

Checking License Status

To display the current license status without making any changes:

qbpp-license

This shows the license type, expiry date, variable limits, and activation usage. The command contacts the license server to refresh the status.

Deactivating a License

To move a license to another machine, first deactivate it on the current machine:

qbpp-license -d

Each license key has a limited number of allowed activations.
Deactivation frees up one activation slot.
The locally cached key is removed as well. To use the license on this machine again, run qbpp-license -k KEY -a (your key is always available in the User Portal).
There is a 24-hour cooldown between consecutive deactivations to prevent abuse.
If the same machine is no longer recognized as activated (for example, its network adapters changed, as can happen on WSL2) and qbpp-license -k KEY -a reports that the activation limit is reached, qbpp-license -k KEY -d on that machine still releases this machine’s existing activation; then run qbpp-license -k KEY -a again. This is also subject to the 24-hour cooldown.
qbpp-license -d only releases the activation of the machine it runs on. To release another machine’s activation, choose it in the User Portal.

Command Reference

Usage: qbpp-license [options]

Options:
  -h, --help          Show help message and exit
  -v, --version       Show version and exit
  -k, --key KEY       Specify a license key (without -a/-d: show info only)
  -a, --activate      Install the license on this machine (node-locked:
                      activate + cache as default key; floating: cache only)
  -d, --deactivate    Remove the license from this machine (node-locked:
                      deactivate + remove cached key; floating: remove only)
  -s, --signup-code   Print today's portal sign-up code and exit
  -t, --time-out SEC  Set the server communication timeout (default: 20 seconds)

Examples

Command	Description
`qbpp-license`	Display current license status
`qbpp-license -s`	Print today’s sign-up code for portal registration
`qbpp-license -k KEY`	Show information about a key (no state change)
`qbpp-license -k KEY -a`	Activate with a specific key
`qbpp-license -d`	Deactivate the license on this machine and remove the cached key
`qbpp-license -t 60`	Check status with a 60-second timeout
`qbpp-license -k KEY -t 60 -a`	Activate with a key and extended timeout

How License Verification Works

qbpp-license command: Always contacts the license server to get the latest status. This may take a few seconds depending on network conditions.
QUBO++ programs: Verify the license using the local cache and do not block on server communication. The server is contacted only when the cache needs to be refreshed (e.g., after a long period without synchronization).
License key storage: When a license is activated, the key is encrypted and cached locally. This allows subsequent runs without setting the key again.

Network and Timeout

If your network is slow or behind a firewall/proxy, the default 20-second timeout may not be enough.

To increase the timeout:

qbpp-license -t 60 -a

If the server is unreachable, QUBO++ falls back to the cached license status. If no cache exists, QUBO++ runs in Fallback Mode (100-variable limit).

Programs work but with limited variables

QUBO++ may be running in Fallback Mode. Check the license status:
```
$ qbpp-license
```
Ensure the license key is set correctly via qbpp-license -k KEY -a or QBPP_LICENSE_KEY.
Re-activate if necessary: qbpp-license -a

“Deactivation cooldown”

There is a 24-hour waiting period between consecutive deactivations.
Wait and try again after the cooldown period has elapsed.

Floating Licenses

Floating licenses allow shared access across multiple machines within an organization. Instead of being permanently locked to a machine, a floating license uses a lease-based mechanism.

When a QUBO++ program starts, it acquires a lease from the license server.
The lease is automatically renewed while the program is running.
When the program exits, the lease is released, making the slot available for other machines.
If the program crashes or the network is lost, the lease expires automatically after a timeout period.
Virtual environments (Docker, VMs, ephemeral containers, etc.) are fully supported. Floating licenses do not bind to a machine fingerprint, so rebuilding a container or starting a fresh VM does not strand any activation slot.

A floating license key can be supplied in two ways.

Activate and cache (persistent machines):

qbpp-license -k F-XXXXXX-XXXXXX-XXXXXX-XXXXXX -a

The key is encrypted and cached locally, so subsequent runs pick it up automatically — convenient on a long-lived workstation or server.

Environment variable (recommended for Docker, CI, and other ephemeral environments):

export QBPP_LICENSE_KEY=F-XXXXXX-XXXXXX-XXXXXX-XXXXXX

The activation cache from qbpp-license -a is stored in the home directory, so it is lost whenever a container or VM is rebuilt — you would otherwise have to re-run qbpp-license -a on every fresh start. Setting QBPP_LICENSE_KEY avoids this entirely: each QUBO++ program reads the key directly from the environment and acquires its lease, with no local activation cache required. Because a floating license is not bound to a machine fingerprint, the same key can be shared across any number of containers without consuming or stranding per-machine activation slots — making the environment variable the preferred way to inject a floating key into a Docker image, docker run -e, Kubernetes secret, or CI job.

The QBPP_LICENSE_KEY value is used only if it is a valid key; a stale or malformed value is ignored (with a warning) and QUBO++ falls back to the cached key, so a bad environment variable never breaks an already-activated machine.