We've released a free tool to extract and display that key, if present: https://neosmart.net/OemKey/

My machine does not have a product key in the BIOS, it is older than that :)

If your machine was OEM preloaded with Windows 7, you can rest assured it has a product key.

It is a ThinkPad T420s. The product key is on the CoA behind the battery not in the BIOS.

Yes, you have 2 cd keys, the key in the CoA sticker, which you have to activate by phone, and the OEM key embedded in the BIOS.

Are you sure? I have looked at the BIOS string and there is no product key. BIOS embedded product keys was something that happened with the Windows 8 release. Are you thinking of something else?

You have a pre-Windows XP machine?