Convert your Windows 2019 Server Eval to retail

Case : After testing your Windows 2019 Server (Standard or Datacenter) Evaluation you want to go retail without installing the server from scratch

Run theses commands from Administrator PowerShell.

Check the version you’re currently running :

DISM /online /Get-CurrentEdition

Check the version you can upgrade to

DISM /online /Get-TargetEditions

To upgrade from Evaluation to Standard :

DISM /Online /Set-Edition:ServerStandard /ProductKey:XXXXX-XXXXX-XXXXX-XXXXX-XXXXX/AcceptEula

To upgrade from Evaluation to DataCenter

DISM /Online /Set-Edition:ServerDataCenter /ProductKey:XXXXX-XXXXX-XXXXX-XXXXX-XXXXX/AcceptEula

Reboot and enjoy.