Hello,

If you downloaded Windows Server 2012r2 Eval, you can convert it to a retail version with “DISM” :

DISM /online /Set-Edition:ServerDatacenter /ProductKey:Y4TGP-NPTV9-HTC2H-7MGQ3-DV4TW /AcceptEula

You’ll need to reboot the server, when it come back online, you can check with :

Get-WindowsEdition -Online

Do note that I used the AVMA key, that imply you have an activated Hyper-V host.