When a Windows client device connects to a published desktop or application on an RDS host, it receives an RDS Per-Device Client Access License (CAL), if the Per-Device licensing mode is configured on the RDS host. By default, the CAL is stored only on the client device.
Beginning with Horizon Client for Windows 4.9, if the client device has a license, it always presents that license. Windows clients that have Horizon Client 4.8 or earlier present a license only if they have a license for the specific pod. If the client device does not present a license, the most up-to-date license that can be found on any pod involved in the published desktop or application launch is used. If a license cannot be found on any pod involved in the launch, the client device's ID is presented to the license server and a license is issued.
For more information, see "Understanding RDS Per-Device Client Access Licensing in Horizon 7" in the Setting Up Published Desktops and Applications in Horizon 7 document.