Once the key is installed, you can manually force activation:

You cannot simply enter a KMS key to convert an "Evaluation" version to "Full." You must use the DISM command first to set the edition.

When installing a volume license edition of , the appropriate GVLK is often pre-installed. However, if you are converting a system from a Multiple Activation Key (MAK) or a retail version, you must manually enter the specific GVLK for your edition: Operating System Edition KMS Client Setup Key (GVLK) Windows Server 2016 Datacenter CB7KF-BWN84-R7R2Y-793K2-8XDDG Windows Server 2016 Standard WC2BQ-8NRM3-FDDYY-2BFGV-KHKQY Windows Server 2016 Essentials JCKRF-N37P4-C2D82-9YXRT-4M63B Source: Microsoft Learn How to Activate Using a KMS Client Key