These steps will also work even if you just have one member of the suite installed. Follow the steps below to use the free LicenseCrawler program to find and then show you your valid Microsoft Office or Office product key. Fortunately, several free software programs called key finder tools are more than capable of finding, and decryptingthat super important Office or product key. Unfortunately, digging it up from there won't be much help because it's encrypted. As you probably know because you've found yourself hereyou must have a valid product key to reinstall Microsoft Office or Office If you haven't already looked, you can avoid the process below by checking for the product key on the disc sleeve, manual, or email receipt that came with your purchase of Office or Beyond that, assuming Microsoft Office is still or was recently installed, the valid product key you need to reinstall Office is stored in the Windows Registry.