Hello arwah abdalla,
Welcome to microsoft Q&A, Thankyou for posting your query here.
please find the below links to know, install and activate RDS with CAL .
https://learn.microsoft.com/en-us/windows-server/remote/remote-desktop-services/rds-install-cals
https://learn.microsoft.com/en-us/windows-server/remote/remote-desktop-services/rds-track-cals
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