For automation enthusiasts, PowerShell can extract license information from a remote server.
If you bought your RDS CALs through a Volume Licensing agreement (Open, Select, Enterprise Agreement), the VLSC is your official repository. how to find rds license key
Limitation: This only shows the key pack ID, not the original product key. You cannot move a Per Device CAL key without a "license reclamation" process. Since Microsoft is moving everything to the cloud,
Since Microsoft is moving everything to the cloud, where you find your key depends on when you bought the license. For automation enthusiasts