There is a licensing grace period of 120 Days during which no license server is required. Microsoft Learn How to Configure Remote Desktop Licensing Mode - TSplus
To force the RDS host to forget a dead/unreachable license server: rds cal license registry key free
If you purchased User CALs but the server is set to Device mode, edit this DWORD: There is a licensing grace period of 120
After a reboot, the grace period restarts — but this is , and Microsoft does not support it for production. Legitimate RDS CALs must be purchased and installed
There is no registry key that provides "free" Remote Desktop Services (RDS) Client Access Licenses (CALs). Legitimate RDS CALs must be purchased and installed through the Remote Desktop Licensing Manager
Sometimes, the GUI fails to point your Session Host to the License Server. You can manually force this via the registry: