When a server is purchased with an OEM Windows Server license, it should come pre-activated. If you
create Windows VMs on that server the licenses may not automatically activate. (Microsoft Windows
Server licensing model allows for one instance of the Windows OS installed on the physical host, plus 2
more copies of the OS on hosted VMs. See Microsoft’s licensing terms for more details. )
There are a few different ways that you’ll find online to “retrieve the license key” via commands, or
from the registry. In an OEM copy of Windows (unverified for other license copies) that key WILL NOT
WORK. For example here is an activated copy of Windows Server 2019 on a Hyper-V host, you can see
the Product Key here ends in GVMMH.
I can pull that full product key from the system using a program or command, or even locate the registry
key and decode it which will give me the full key.
However, this is not the actual key that you need. With an OEM windows server license this is a digital
license that is attached to the physical machine itself, it is not the same as buying a license and then
activating it.
Microsoft and the vendor you ordered the server from will not be able to provide you with the license
key that came with the server – the vendor will likely provide an installer ISO file for the copy of
windows you purchased, for example in Dell’s Digital Locker but you won’t find the key there.
The only place that you will find that key is on a sticker on the outside of the server itself. Here is a link
to Dell’s site giving an example of where this key might be found for one of their PowerEdge servers:
https://www.dell.com/support/kbdoc/en-us/000132520/microsoft-oem-windows-server-certificate-of-
authenticity-on-dell-emc-poweredge-servers
If the VMs on your host are not activating, you may see error codes such as this one: 0xC004F057
Once you retrieve the key from the sticker on the server you can try the standard method of just clicking
on the button to change the product key. Likely you will need to manually install with these commands
instead:
(Run in an elevated command prompt on the VM you are trying to activate Windows on)
slmgr /upk (to uninstall the temp license)
slmgr /ipk <lincense key> (to install the license)
slmgr /ato (to register the license with Microsoft)