3.4.2 Licensing
The use license (UL) describes what usage policies apply to the user while accessing a particular protected content file. It also contains the content key that is encrypted with the user's RAC public key. The UL is the authorization token that allows a user to access protected content.
To retrieve the UL, the RMS client application issues an AcquireLicense request. In an AcquireLicense request, the client sends the publishing license (PL) that came with the content along with the user's RAC and any application data to the RMS server. The server validates the RAC and PL and passes through any application data that is present. If validation succeeds and the user is granted access, the server generates a use license and returns it to the client. More details on the AcquireLicense request can be found in [MS-RMPR] section 3.4.4.1.