The RD Session Host server determines whether an RDS CAL is required when a user or device connects to it. The Remote Desktop license server is then contacted by the RD Session Host server to seek an RDS CAL.
When a client receives a proper RDS CAL from a license server, they can connect to the RD Session Host server and, from there, to the desktop or applications they’re trying to utilize.
There is a 120-day licensing grace period during which a license server is not necessary. After the grace period expires, clients cannot access an RD Session Host server unless they have a current RDS CAL issued by a license server.
The first time a device connects to the RD Session Host while using the Per Device model, a temporary license is provided. If the license server is turned on and there are still RDS CALs available when the device joins a second time, the license server will issue a permanent RDS Per Device CAL.
How long do user CALs last?
The duration of a temporary RDS CAL is 52 to 89 days.