Beware - this does not work with downloaded trial version

This is a licence for the OEM version of Office, that would normally be pre-installed on a new computer by the manufacturer. If you have downloaded the trial version of Office from the Microsoft website and are trying to validate it when the trial period runs out, this licence won't work. I know because I tried. You have to buy a more expensive retail version (or try to get hold of the OEM Pre-installation Kit).