# License options

ACEMD is dual-licensed. The right license depends on whether you're doing commercial work and how your hardware is organised.

## Non-commercial license

Free for academic and non-profit use under the [Acellera Software Not-for-Profit License Agreement](../reference/license.md). No license file is required to run ACEMD non-commercially; the package prints the license terms on first run and registration is optional (and silences the message).

If your work is funded by, conducted at, or otherwise tied to a for-profit organisation, you need a **commercial** license — see below.

## Commercial license

Required for any commercial use, including fee-based services. Contact [info@acellera.com](mailto:info@acellera.com) for terms.

Commercial licenses come in three deployment shapes. Pick the one that matches how your users access compute:

### Node-locked

A `license.dat` file bound to the **MAC address** of a specific machine.

- **Best for** individual workstations or small HPC clusters where ACEMD only runs on a handful of fixed hosts.
- **You provide** the MAC address(es) at purchase. The license is issued for those hosts and won't validate on other hardware.
- See [Install a node-locked license](../how-to/install-a-node-locked-license.md).

### Floating

A license file deployed on a single **license server** machine; clients check out a license at runtime from a fixed pool.

- **Best for** larger HPC clusters where any of many nodes might run ACEMD, and you don't want to bind to specific node MACs.
- **You provide** the MAC of the license-server host plus the maximum concurrent-license count.
- **Clients need** network access (default TCP `27000`) to the license server.
- See [Deploy a floating license server](../how-to/deploy-a-floating-license-server.md).

### Cloud

Same protocol as floating, but the license server is **hosted by Acellera**.

- **Best for** cloud/virtualised environments where MAC addresses are unstable and you don't want to run your own license server.
- **You receive** a public IP and port; set `ACELLERA_LICENSE_SERVER=<port>@<ip>` on each client.
- **Clients need** network access to Acellera's server.

## Which one for which situation

| Situation                                              | Pick                  |
|--------------------------------------------------------|-----------------------|
| Solo workstation                                       | Non-commercial or node-locked |
| Small lab, a few fixed GPU hosts                       | Node-locked           |
| HPC cluster, many shared nodes                         | Floating              |
| Cloud / Kubernetes / spot instances                    | Cloud                 |

## How ACEMD finds the license at runtime

ACEMD looks for a license in the following places (both the American and British spellings are accepted for each environment variable):

- Environment variables `ACELLERA_LICENSE_SERVER` / `ACELLERA_LICENCE_SERVER` — for floating and cloud.
- Environment variables `ACELLERA_LICENSE_FILE` / `ACELLERA_LICENCE_FILE` — explicit path to a node-locked file.
- `/opt/acellera/license.dat` (or `licence.dat`) — system-wide node-locked location.
- `~/.acellera/license.dat` (or `licence.dat`) — per-user node-locked location.

If **any** of these variables is set or any of these files exists, ACEMD hands off to the bundled `license-checker` binary, which performs the actual validation and decides which license to use. The Python layer does not itself rank the candidates or enforce a precedence between them — that logic lives in the external checker.

`acemd --license` runs the checker and prints its report so you can verify a license install. Note that `acemd --license` always exits with status `0`; it is informational and does not return a pass/fail exit code, so don't rely on its exit status in scripts — read its output instead.

## See also

- [Install a node-locked license](../how-to/install-a-node-locked-license.md)
- [Deploy a floating license server](../how-to/deploy-a-floating-license-server.md)
- [License text](../reference/license.md)