# License Key

Without a key, Workflow Engine runs as Workflow Engine Free: personal use and internal commercial use, with attribution, under the [Workflow
Engine Free terms](https://workflowengine.io/agreements/eula/#workflow-engine-free) and within its limits on
[schemes](https://docs.workflowengine.io/get-started/concepts/scheme/) and threads. Workflow Engine Team and Complete license the same internal use and lift the limits; a
public web app or SaaS needs Workflow Engine NEO Subscription or Workflow Engine NEO SaaS. A license key is a string provided by OptimaJet
after purchase or trial registration. Register it with `WorkflowRuntime` before calling `Start()`.

## Get a trial license key

You can obtain a free 30-day trial key at [trial.workflowengine.io](https://trial.workflowengine.io). No credit card is required.

### Via the web form

1. Open [trial.workflowengine.io](https://trial.workflowengine.io) in your browser.
2. Enter your **company name** and your **business email** (personal email domains such as gmail.com are not accepted).
3. Click **Get Trial Key**.
4. Check your inbox - the license key and setup instructions are sent to the email you provided.

The key has the `TRIAL-` prefix and unlocks all features for 30 days. When the trial expires, the runtime falls back to Workflow Engine Free
mode with the same caps as an unlicensed installation.

### Via API (for LLM agents and automation)

The trial portal exposes a programmatic API for agents and automated workflows. The API reference is available
at [trial.workflowengine.io/llms.txt](https://trial.workflowengine.io/llms.txt).

```json
POST https://trial.workflowengine.io/api/trial/llm
Content-Type: application/json

{
  "email": "user@company.com",
  "companyName": "Company Name"
}
```

A successful response returns the license key directly and also sends it by email:

```json
{
  "success": true,
  "message": "Check your email. We've sent the trial license key and setup instructions.",
  "licenseKey": "TRIAL-..."
}
```

**Limits:**

- Maximum 3 trial keys per email address (lifetime).
- Business email required - personal and disposable domains are rejected.
- Rate limit: one request per email per 24 hours.
- The key is also sent by email for reference.

## Purchase a commercial license key

Prices are on the [Workflow Engine pricing](https://workflowengine.io/pricing/) page. To buy a license, [contact
sales](https://workflowengine.io/contacts/) or write to [hello@optimajet.com](mailto:hello@optimajet.com). Once you receive your key, it
will begin with a customer identifier prefix (your company name for commercial keys or `TRIAL-` for trial keys).

## Register the license key

Call the static method `WorkflowRuntime.RegisterLicense` once before creating any runtime instance. This is the recommended approach for
console apps and worker services:

```csharp filename="Program.cs"
WorkflowRuntime.RegisterLicense("YOUR-LICENSE-KEY-STRING");

var runtime = new WorkflowRuntime()
    .WithPersistenceProvider(persistenceProvider)
    .AsSingleServer()
    .Start();
```

The key must be registered **before** calling `.Start()`. The key is validated at startup; an invalid or expired key throws
`InvalidLicenseException` or `LicenseExpiredException`.

## Store the key in configuration

Do not hard-code the key in source code. Read it from application configuration:

```json filename="appsettings.json"
{
  "WorkflowEngine": {
    "LicenseKey": "YOUR-LICENSE-KEY-STRING"
  }
}
```

```csharp filename="Program.cs"
string licenseKey = builder.Configuration["WorkflowEngine:LicenseKey"]
    ?? throw new InvalidOperationException("Workflow Engine license key is not configured.");

WorkflowRuntime.RegisterLicense(licenseKey);

var runtime = new WorkflowRuntime()
    .WithPersistenceProvider(persistenceProvider)
    .AsSingleServer()
    .Start();
```

For production, store the key in a secrets manager (Azure Key Vault, AWS Secrets Manager, Kubernetes secrets) and inject it into
configuration at runtime.

## Workflow Engine Free limits

Without a license key, or with an expired key, Workflow Engine runs in Workflow Engine Free mode:

Table: Workflow Engine Free limits

| Limit                                        | Workflow Engine Free                                 |
|----------------------------------------------|------------------------------------------------------|
| Unique schemes in the process cache          | 10                                                   |
| Concurrent runtime operations (semaphore)    | 4                                                    |
| Activities, transitions, commands per scheme | Unlimited                                            |
| Designer                                     | Fully functional with Workflow Engine Free indicator |

Workflow Engine Free is suitable for development, evaluation, and small projects. It does not watermark or disable functionality - the
scheme and concurrency limits are the only restrictions.

## Verify the license at startup

Check the current license restrictions by reading `WorkflowRuntime.GetLicenseRestrictions()`:

```csharp
var restrictions = WorkflowRuntime.GetLicenseRestrictions();

if (restrictions.MaxNumberOfSchemes <= 10)
{
    logger.LogWarning(
        "Workflow Engine is running in Workflow Engine Free mode. " +
        "Scheme and thread limits apply.");
}
```

This method always returns the active restrictions - Workflow Engine Free defaults if no license key is registered, or the upgraded values
if a valid key was applied.

## Handle license expiry

Most license keys have an expiry date - typically 12 months from purchase. When a key expires, the runtime switches
to [Workflow Engine Free mode](#workflow-engine-free-limits) - the same limits as running without a license.

Perpetual keys do not expire. Once registered, they remain valid indefinitely.

To restore full functionality after expiry, replace the expired key with a new one in your configuration and restart the application. No
database changes are needed.

For trial keys, visit [trial.workflowengine.io](https://trial.workflowengine.io) before the current key expires.

## Deploy licenses across multiple servers

In a multi-server deployment, each runtime node reads the license key from its own configuration. All nodes must use the same key. There is
no per-node or per-seat licensing - the key covers the entire deployment.

## See also

- [Workflow Engine Editions](https://docs.workflowengine.io/evaluate/workflow-engine-editions/): Compare Free, commercial, and NEO editions.
- [Workflow Engine Features](https://docs.workflowengine.io/evaluate/workflow-engine-features/): Browse Workflow Engine features and their edition requirements.
- [Install](https://docs.workflowengine.io/get-started/install-workflow-engine/): Set up the runtime and register your license key.

## Frequently asked questions

**Where do I buy or renew a license key?**

Prices are on the Workflow Engine pricing page, and the sales team at [hello@optimajet.com](mailto:hello@optimajet.com) handles purchases
and renewals. Licenses are available for annual subscription or perpetual purchase.

**Where do I get a trial key?**

Visit [trial.workflowengine.io](https://trial.workflowengine.io), enter your company name and business email, and click **Get Trial Key**.
The key is sent to your email. You can also request one programmatically via `POST /api/trial/llm` -
see [trial.workflowengine.io/llms.txt](https://trial.workflowengine.io/llms.txt) for the API reference. The trial key has the `TRIAL-`
prefix and works the same way as a commercial key for 30 days.

**Can I use one license key in both staging and production?**

Yes. The same key works in production, staging, and development; those environments do not require additional purchases.

**What happens if I restart the application after the license expires?**

The runtime switches to [Workflow Engine Free mode](#workflow-engine-free-limits) - processes continue to run and new instances can be
created, but the Workflow Engine Free limits apply. Renew the key and restart to restore full functionality.

**Is the key validated online?**

No. License validation is performed locally - the key string encodes your entitlements and is verified without a network call. The runtime
does not phone home.

**How is the key structured?**

License keys contain a customer identifier prefix and base64-encoded license data. The prefix matches the customer identifier encoded in the
data to prevent key sharing. The data includes expiry date, feature restrictions, and a cryptographic signature.