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.
If the client device has a license, it always presents that license. 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" in the Setting Up Published Desktops and Applications in Horizon document.