Upgrading to Win10 invalid key

Hi All,

I have a machine running Windows 7 and have finally got around to upgrading it to Win10.  There are a number of articles online saying that since Nov 2020 the Windows 10 ISO allows you to upgrade your Win 7 installation using the Win 7 key.  This should happen without asking for the key itself.

Unfortunately, when I try this, it asks me for a key. Online it says the Win 7 key will work but I am having no joy.  There appears to be 3 keys on my systems

1. If I go to system in control panel I get one key which has OEM in the middle

2. The sticker on the PC has a different key

3. Using a tool to get the key I get a different key again.

I have tried all 3 and none seem to work.  Looking in Windows 7 it also downloaded an update which then says it will auto activate in 3 days but clicking "activate now" and entering the 3 keys above also fails.

Anyone have any idea how to do this as I have been searching online and have drawn a blank.

Thanks in advance for your help

Lee.