Conclusion RDS CALs are a required, enforceable mechanism for legally allowing remote connections to Windows Server. Registry edits or “free” keys do not substitute for valid licensing and carry legal, security, and operational risks. Organizations should select the appropriate CAL model, explore volume or cloud licensing options, centralize and document licensing, and seek expert advice to stay compliant while optimizing cost.

: In Licensing Manager, right-click and "Activate Server," or use the Microsoft activation website.