There are multiple features we can use on Clearpass each of which requires a license. These include Platform, Access, Onguard and Onboard.
ClearPass Platform Activation Key:
The ClearPass Platform License is the base-level license and enables ClearPass on the appliance, including the Policy Manager and Guest user interface. You must have a ClearPass Platform license for every appliance.
ClearPass supports three Application License types: Access, OnGuard, and Onboard.
Check out the video below on how to add these licenses on Clearpass: