Error: The remote session was disconnected because there are no Remote Desktop License Servers available to provide a license. Please contact the server administrator.
Solution:
1. Go to registry, navigate to
HKLM\System\CurrentControlSet\Control\Terminal Server\RCM
2. Delete the
GracePeriod folder. (if unable to delete, right click on the
GracePeriod folder, click
Permission. Assign Full Control)

3. Then restart the server.
4. To validate RD Licensing configuration completed. Go to
Server Manager, select
Remote Desktop Services, on the
Overview, under the
Deployment Overview, click
Task, select
Edit Deployment Properties.
5. Click on RD Licensing, make
Remote Desktop Licensing mode selected.(Per Device\Per User)