Article from: http://ravingroo.com/949/server-2012-rds-no-remote-desktop-license-servers-available/
Assuming your licensing configuration is valid and you have licenses available, if you receive the above error the problem is likely an expired “GracePeriod” registry key. In our case, this “GracePeriod” key found its way into the registry at some point when this template was built. And since it was built many months ago, this grace period has since expired. You’d think RDS would be smart enough to see the license server in the domain and act accordingly, in this case, talk to the license server, confirm there are available licenses and then either ignore the grace period key or remove it. But nope, it just gives you the above error instead.
Lucky for you the fix is easy. You simply delete this key manually.
Open up the registry editor and browse to:
\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server\RCM
You should see a key called “GracePeriod”. Right-click this key and then click “Permissions.” Assign yourself (or Administrators, assuming you are part of that group) “Full Control” and then DELETE the key. You won’t be able to delete it unless you give yourself at least read/write permission (Full Control is just expedient). Now reboot the server and everything will be right as rain.
