A Microsoft RDS client cannot connect to a Microsoft RDS server and use the server’s apps without an RDS CAL. Therefore, it is crucial that administrators regularly verify whether or not the Microsoft RDS License server has enough RDS CALs to satisfy the server’s present and projected user traffic.
Administrators can utilize the RDS CAL Licenses Utilization test to do this.
This test provides the amount, type, and usage of RDS CALs installed on the Microsoft RDS License server under a certain Key pack ID and purchased under a particular License program or Purchase method for each Microsoft RDS server that is administered by the license server (this can be, Unknown, Retail, Built-in, Volume, Concurrent, Temporary, Open).
You might choose to limit license usage to just one Microsoft RDS server (and not by key pack ID and purchase method). These statistics allow you to quickly identify potential licensing shortages and pinpoint the Microsoft RDS server that may soon run out of licenses.
What happens if I run out of RDS CALs?
If there are no RDS Device CALs available, none can be issued permanently, and the issued CAL is not replaced on the client’s device. A Remote Desktop session can still be started if there is a working temporary CAL; otherwise, the request is turned down and the session is not allowed to start.