Upgrading to Windows 10 is now complete, and I want to clean install Windows 10. I am wondering if OPA-Backup for office 2013 would work on Windows 10. The instruction says that I should reinstall Office using the same serial and run OPA before the first run of Office; however, the installation disk I have do not ask for serial when installing office. I have to run it first to enter serial, and I can't find a retail installation disk that asks for serial when installing. If this doesn't work then are there any other ways to back up my activation? Thanks.