WinXP RDesktop License Reset

Delete the mslicensing key from the registry in the path

HKLM/SOFTWARE/MICROSOFT/MSlicensing

delete the complete MSlicensing key from the client computer which tries to establish a remote session.

after u delete this key , the client machine would once again be issue a temp license and it would be valid for another 120 days in case of 2003 licensing server .

Solution: If the previous solution does not resolve this problem, create a backup of the MSLicensing registry key and its subkeys on the client, and then remove the original key and subkeys by doing the following:

1. On the client, navigate to the following registry subkey: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSLicensing.

2. Click MSLicensing.

3. On the Registry menu, click Export Registry File.

4. In the File name box, type mslicensingbackup, and then click Save.

5. If you need to restore this registry key in the future, double-click mslicensingbackup.reg.

6. On the Edit menu, click Delete, and then click Yes to confirm the deletion of the MSLicensing registry subkey.

7. Close Registry Editor, and then restart the computer.

When the client is restarted, the missing registry key is rebuilt.To resolve this problem automatically, click the Fix this problem link. Then, click Run in the File Download dialog box.

http://technet.microsoft.com/en-us/library/cc756826(WS.10).aspx#BKMK_4
http://www.computing.net/answers/windows-2003/terminal-services-license-issue/3295.html