For most modern Windows Server setups, the key isn't stored in a text file; it’s managed through a specific GUI.
If you purchased your RDS licenses through the Microsoft Volume Licensing Service Center (VLSC), you can find your license key on the VLSC website. Here's how: how to find rds license key
If you work for an organization that purchased RDS CALs under a Volume Licensing agreement, this is your primary source of truth. For most modern Windows Server setups, the key
Here’s how to locate it:
If the licenses are already installed on your server, the is the primary place to find details about them. For most modern Windows Server setups