If you need to transfort your evaluation windows to RTM here are relative commands:
1. Check the version installed:
DISM / online / Get-CurrentEdition
If you want to verify that version can upgrade the system:
DISM / online / Get-TargetEditions
To upgrade you need to type:
DISM / online / Set-Edition: ServerVersion / ProductKey: XXXXX-XXXXX-XXXXX-XXXXX-XXXXX / AcceptEula
[from http://epansecco.net/2014/10/21/windows-server-2012-r2-da-evaluation-version-a-rtm/]
