@lebrun78 I don’t use the FOG Client so I can’t really speak to its activation of the target computer. But I believe if its enabled in the fog management web ui and you have entered either a OEM key or VLK key in the host configuration for that computer the FOG Client will try to activate it. I believe this is outside of any sysprep process.
I can tell you how I use MDT, sysprep and FOG.
I do use MDT to build my golden image each time using the lite touch process. At the end of imaging I run through a quick quality check to ensure everything is setup as it should be then I run a batch file that MDT drops in a certain directory that calls sysprep and points to a custom unattend.xml file. Sysprep then powers off the computer. I capture it with FOG. Then deploy it. I have a post install script update the unattend.xml file on the target computer with the computer’s name, target OU, timezone, KMS Key, and a few other things. When the computer boots and runs WinSetup/OOBE the target computer connects itself to AD and in the proper OU from the unattend.xml file. At the end of OOBE WinSetup calls the setupcomplete.cmd and runs a command cscript c:\Windows\System32\slmgr.vbs /ato that activates windows.