Windows 2016 - How to convert evaluation to licensed version

You can verify if your windows 2016 version is in evaluation mode:

start --> cmd (Administrative permissions) --> DISM /online /Get-CurrentEdition

"Currrent Edition : ServerStandardEval "

start --> cmd (Administrative permissions) -->  winver

If you want to convert license:

start --> cmd (Administrative permissions) --> DISM /online /Get-TargetEditions

You will have these options:

ServerStandard

ServerDatacenter

start --> cmd (Administrative permissions) --> DISM /online /Set-Edition: /ProductKey:XXXXX-XXXXX-XXXXX-XXXXX-XXXXX /AcceptEula

REMARK: This procedure work only if a KMS host server is working in the lan (and KMS role correctly configured)