I recently ran into an issue where I wanted to test a deployment using Windows Server 2019 Storage Migration Service feature. It turns out an Evaluation installation does not support storage migration service and it will not appears to be missing in the Windows Admin Center.
I needed to upgrade Windows Server 2019 Evaluation to Standard edition. which is fortunately very easy!
First open up a Powershell window and run as Administrator.
Enter the following command:
DISM /Online /Set-Edition:ServerStandard /ProductKey:N69G4-B89J2-4G8F4-WWYCC-J464C /AcceptEula
DISM will proceed to make the required changes and will request a reboot. Press Y to reboot the server.
Once the server has rebooted, log back in and open up Powershell again and type:
DISM /Online /Get-CurrentEdition
Congratulations you now have standard edition installed!