> ## Documentation Index
> Fetch the complete documentation index at: https://help.cryptolens.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Basics of Devolens

> Core concepts for getting started with Devolens licensing.

Devolens (formerly Cryptolens) helps you add licensing to your software, automate license delivery, and manage how customers access your products.

At a high level, a typical integration has three parts:

* **Licensing data**: products, license keys, customers, features, activations, and metadata.
* **Your application**: verifies a license and decides what functionality to unlock.
* **Integration layer**: client SDKs or direct Web API calls connect your application and backend systems to Devolens.

## Runtime license checks

Inside your application, licensing usually becomes a simple decision: is this license valid, and what should the user be allowed to do?

```c# theme={null}
if (license.HasFeature(1)
           .HasNotExpired()
           .IsValid())
{
    // Unlock the feature.
}
else
{
    // Show an activation, renewal, or upgrade message.
}
```

The exact code depends on your platform and licensing model. See [key verification](/examples/key-verification) for a complete implementation.

## What to learn first

Start with the core objects that most licensing models are built from, then learn how your application communicates with Devolens.

* [Products, keys, customers, and activations](/basics/product-and-keys) explains the main objects you manage in Devolens.
* [Web API](/basics/webapi) explains how applications, backend systems, and integrations communicate with Devolens.
* [Licensing models](/licensing-models/index) shows common ways to combine these concepts, such as subscriptions, floating licenses, usage-based licensing, and user authentication.

## Next

* [Follow the getting started guide](/getting-started/getting-started-guide)
* [Choose a client SDK](/libraries)
* [Review common licensing models](/licensing-models/index)