I installed W10 to an old desktop I had. At install-time, I selected no product key at this time and then selected Home (choices were Home and Pro). Installed W10, and afterwards I wasn't activated. I hit troubleshooting, it said something about upgrading my edition of Windows since I had a Pro key tied to that computer for some reason, went through with it, rebooted, and now I'm activated on Pro. I signed in with a MS account. I didn't select Insider until after the edition upgrade. I didn't purchase a W10 Pro key. I'm almost certain I've never had a legitimate key for any edition of Windows I had on that computer. Any ideas as to why this computer has Pro?