I already had Windows 10 Home running on Boot Camp on Sierra on a late 2013 iMac, a lProduct Key had been purchased and the installation was activated. Using a trial version of Parallels Desktop 12 I am attempting to use Boot Camp in Parallels. It is proving impossible to get this activated, I have used the existing Product Key but that fails with Error code 0xC004C003 with the suggestion to go the the Store to buy genuine Windows. The Parallels Tools have been run, I had thought that on of the functions of the Tools was to handle this situation. Is is still possible to use Windows on Boot Camp both directly by booting into it and from within macOS, or has Windows 10 changed something so that it is now case either or?