Easiest way to install & update is to use the Retail ISO that was linked to somewhere on kitz ... sorry forgot where.
If you mount the .ISO or 'burnt to disc copy' in Win7 and run setup it will install.
As long as you have a properly registered copy of Win 7 it will work and
should activate as well.
I did it on a test PC but wanted to see what the 100% original Experience was from Microsoft, as they intend all users to upgrade.
These are the keys you should end up registered with:
Windows 10 Home - YTMG3-N6DKC-DKB77-7M9GH-8HVX7
Windows 10 Home SL- BT79Q-G7N6G-PGBYW-4YWX6-6F4BT
Windows 10 Pro - VK7JG-NPHTM-C97JM-9MPGT-3V66T
Windows 10 Pro VL-MAK - QJNXR-7D97Q-K7WH4-RYWQ8-6MT6Y
AFAIK:
It appears everyone is getting registered with these keys, so no more passing keys etc around for the naughty people.
Your activation is a unique Machine ID which no doubt was calculated by the GWX.exe stuff downloaded to your Windows machine.
When you registered interest in the free upgrade MS recorded the Unique machine ID.
Change too much on your machine and your unique machine ID will not match ?!
That will be interesting as I change hardware quite a lot. Always chopping & changing configs etc.
I wonder if the Unique machine ID is checked periodically or when major updates are made. ?