Windows operating system license requirements
The Microsoft Server operating system software used by the ADS/ADX requires licenses called Client Access Licenses (CALs). A CAL is a license that gives you the right to access the services of the server. Two types of Microsoft operating system CALs are available: a device-based CAL and a user-based CAL. You need to purchase the CALs separately from the ADS/ADX server.
For more information on CALs, refer to https://www.microsoft.com/en-us/licensing/product-licensing/client-access-license.