Windows Logs - System - Event ID 4105 (Warning):
The Remote Desktop license server cannot update the license attributes for user "UserName" in the Active Directory Domain "yourdomain". Ensure that the computer account for the license server is a member of Terminal Server License Servers group in Active Directory domain "yourdomain".
If the license server is installed on a domain controller, the Network Service account also needs to be a member of the Terminal Server License Servers group.
If the license server is installed on a domain controller, after you have added the appropriate accounts to the Terminal Server License Servers group, you must restart the Remote Desktop Licensing service to track or report the usage of RDS Per User CALs.
Find user "UserName"
Go to Security tab
Click Add and type Terminal Server License Servers, click OK
Allow "Read Terminal Server license server" and "Write Terminal Server license server" permissions.
After next logon to terminal server you will see Information message id 4143 under Microsoft-Windows-TerminalServices-Licensing/Admin log.