$30 Windows Upgrade - help finding post please

I tried doing a search for the thread regarding this offer, but could not find it. Is anyone able to help please?

Hubby bought and installed the upgrade, but his hard drive recently died and he's had to replace it. He's unable to find any of the documentation about it (no longer has any emails regarding this,) so is unable to reinstall the upgrade. About the only option left is to find a record of the credit card transaction and give Microsoft a call. I'm trying to ascertain roughly when he'd have gotten it to know where in the CC records to search for it.

Any help would be greatly appreciated.