Control Panel> Systems and Security> System: This page will contain the 'Change Product Key' link at the bottom right of the page. What is the link for? I put in my genuine Win 8.1 Pro Full Retail product key in the 'Change Product Key' link dialogue, expecting to be given a new product key. However, the dialogue box closed with a cryptic message 'We are all done', and there was no further communication. What is the 'Change Product Key' link for? MSDN didn't seem to know.