Windows has a couple different places where you can find different product keys such as the OEM key from vendors such as Dell, Lenovo, etc; and the BackupProductKeyDefault in the registry.

To find the OEM Key you can find your key using this powershell command.

wmic path SoftwareLicensingService get OA3xOriginalProductKey 

or

powershell "(Get-WmiObject -query 'select * from SoftwareLicensingService').OA3xOriginalProductKey"