Dear Rosario Sayago Vaquez,
I believe that you need to recover the Windows Server 2016 Standard product key after a hardware issue.
1) If it’s an OEM license (came with the server) and the machine still boots:
Please run these commands in an elevated Command Prompt:
wmic path SoftwareLicensingService get OA3xOriginalProductKey
slmgr /dli
slmgr /dlv
If the motherboard was replaced, OEM licenses are tied to the original board and usually aren’t transferable. In that case, you may need to contact the hardware manufacturer.
2) If it’s a Retail license:
Please check your purchase email or your Microsoft account for the key.
3) If it’s a Volume license (MAK/KMS):
Sign in to VLSC to retrieve your MAK. With KMS you use a GVLK (generic key) with a KMS host.
4) If the system doesn’t boot but you still have the drive:
We can attempt an offline read of the registry on another PC to see if a key is stored:
reg load HKLM\OFFLINE "X:\Windows\System32\config\SOFTWARE"
(Get-ItemProperty 'HKLM:\OFFLINE\Microsoft\Windows NT\CurrentVersion\SoftwareProtectionPlatform').BackupProductKeyDefault
reg unload HKLM\OFFLINE
Note: Volume/KMS installs usually show only the generic key.
I hope you may find this helpful!
Finn.