Editing the Windows Registry carries risks. Incorrectly modifying or deleting registry keys can cause system instability or prevent the operating system from booting. Always back up the registry before making changes.
Per User CALs are not auto-applied — they require tracking in AD or manual installation. Registry only stores the mode preference. Fix: Ensure Per User CALs are actually installed on the license server (RD Licensing Manager → Install Licenses).
The most frequent mistake is setting the LicensingMode value incorrectly. For instance, if you have installed Per Device CALs but configure the registry for Per User (setting value to 4), the server will fail to issue licenses, and users will encounter connection errors.
A restart is required for this change to take effect and for the server to reach out to the specified license server. 4. Verify Activation rds cal license registry key
: HKEY_LOCAL_MACHINE\Software\Microsoft\MSLicensing Function : Contains issued licenses for RDP clients. Macintosh RDP clients store licenses locally at /users/Shared/Microsoft/RDC Crucial Server Information/ .
Instead of manually editing SpecifiedLicenseServers , set the policy “Use the specified license servers” via GPO. Registry edits should only be temporary.
: Defines target servers under HKLM\SYSTEM\CurrentControlSet\Services\TermService\Parameters\LicenseServers . Managing the 120-Day Grace Period ("TimeBomb") Editing the Windows Registry carries risks
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server\RCM Value Name SpecifiedLicenseServers (Multi-String) : Enter the FQDN or IP of your license server. Microsoft Learn 2. Resetting the 120-Day Grace Period
When you decommission an old license server, your RDS host may still attempt to contact it. Removing the server’s entry from SpecifiedLicenseServers forces the host to fail over to another server.
Configuring Remote Desktop Services (RDS) through the Windows Registry is a common task for system administrators troubleshooting licensing issues or setting up session hosts without using Group Policy Objects (GPO). Primary Registry Key Locations Per User CALs are not auto-applied — they
If you delete the MSLicensing key on a Windows Vista or later client and subsequent connection attempts fail with "An Error occurred in the Licensing Protocol," restart the Remote Desktop Connection as an administrator. This ensures the client has permissions to rewrite the necessary registry keys.
LicenseServers (String) — The FQDN of your license server. Local/Manual Configuration:
RDS session host shows “Per User” mode, but users get a temporary license expiration warning. Check: