The remote computer disconnected the session because of an error in the licensing protocol.

If you get the error below there are a few things that could be wrong and a few ways to fix it.

The key HKLM\SOFTWARE\Microsoft\MSLicensing\ could be corrupt or it may contain values that already exist for another computer in the environment.

First thing to do is to delete anything under the MSLicensing key and restart the computer.

If you are using XP this should be enough but if you are using Vista/7/8 you may have to run the Remote Desktop Connection as Administrator to be able to recreate they deleted keys.

Sometimes the above actions won't work, the keys won't get recreated and you will be unable to RDP to any computer.

If that's the case then open a command prompt with elevated privileges and run:

Regsvr32 /u mstscax.dll
Regsvr32 /s mstscax.dll

This will recreate the deleted keys.