I had email problems and needed to find out if I had some trial version of Norton pre-installed. [http://community.norton.com/en/forums/how-can-i-tell-if-my-six-months-old-pc-came-trial-version-nis#comment-7040181] I didn't but had a McAfee version.
I then asked for help on the Microsoft Community [http://answers.microsoft.com/en-us/outlook_com/forum/opeople-oother/since-the-change-i-cannot-send-emails-to-a-group/4b73c88b-5e76-48a6-8ea9-3ee833b046f5]. During this work I uninstalled then reinstalled NIS, followed by using the Norton Removal Tool. During that process, up popped a Norton article "Reinstalling your Norton Product after you run the Norton Removal Tool".
So Norton knew there would be a reinstall but when I followed the link it told me my desk was full, that I would have to buy a new product key. No chance of that, of course! I checked my subscriptions and found three devices: Win7 upgraded to Win10, my XP and my Win10, which I'd just uninstalled. The only way that I could progress was to remove it from the WP, which I did. I wondered if the Win10 would be shown twice but I've checked again just now and it hasn't - I have the two Win PCs so I'll 'reinstate' the XP. Can't this process be tidied up so clicking "this is a reinstall" or similar will not confuse the seats check?