# Licensing Xamarin Applications

## Content

ComponentOne Xamarin applications support application licensing through the NuGet package build scripts included with the controls.
To build and properly license a Xamarin application, each developer or build machine must have an activated ComponentOne serial key. For instructions, see **[Activating a Serial Key](https://developer.mescius.com/componentone/docs/license/online-license/activating-serial-key "https://developer.mescius.com/componentone/docs/license/online-license/activating-serial-key")**.

## How Licensing Works

When a Xamarin application is built on a machine with an activated serial key:

* A unique run-time license file is generated during the build process
* The license file is embedded into the application as a resource
* The embedded license enables the application to run without requiring a license on the end user’s machine

The run-time license file has the following extension format:

* **.gclicx**

Before embedding, the license file can usually be found in the build output directory, such as:

* `obj/Debug`
* `obj/Release`

The run-time license file **must be distributed with the application** as an embedded resource.

## Manual License Generation

In advanced scenarios, such as custom build processes, build agents, or specialized packaging workflows, you can manually generate the run-time license file.
For instructions, see **[Create Runtime License](https://developer.mescius.com/componentone/docs/license/online-license/common-licensing-scenarios/create-runtime-license "https://developer.mescius.com/componentone/docs/license/online-license/common-licensing-scenarios/create-runtime-license")**.
If you are working with build agents or licensing user controls, see **[Additional Licensing Scenarios](https://developer.mescius.com/componentone/docs/license/online-license/common-licensing-scenarios "https://developer.mescius.com/componentone/docs/license/online-license/common-licensing-scenarios")**.

>type=note
> Notes
>
> * Build-script–based licensing requires **Visual Studio 2019 or later** and **ComponentOne version 2020 v2 or later**.
> * For licensing older ComponentOne versions, see **[Create Runtime App Key](https://developer.mescius.com/componentone/docs/license/online-license/common-licensing-scenarios/create-runtime-app-key "https://developer.mescius.com/componentone/docs/license/online-license/common-licensing-scenarios/create-runtime-app-key")**.