New
#31
First you will need to see a previous version installed an upgraded over before planning any clean install on a new build or any other machine! Otherwise you'll be waiting an eternity to see it activate and it won't simply because there won't be any record of it on the MS activation servers. They may be doing away with product keys but not hardware profiles anytime soon!
As for a second 7 Pro case here I had put a clean install on that when shrinking down the 7 primary for the second 10 would go onto and didn't expect to see 7 activated but wasn't ready to upgrade over the 7 install there until a day ago where upon finding the 10 upgrade activated the nag appeared until selecting Waterfox(64bit offspring of FF) was made the default browser in the List of items to be seen made default you have to go over before all that is taken care of.
As far as the clean install upon rebooting into that once I found the upgrade was activated during the install there I went in and found the clean install put on a day earlier was activated as well. But it still took the upgrade on that build to see it happen.