To be clear, you did this, right?
1. Have a properly activated version of Windows 7 SP1 installed
2. Go to
Windows 10 (the ISO download site)
3. Download the tool (32 bit or 64 bit, depending on what you need)
4. Run the tool, select the "Upgrade this PC" option
If you have done the steps above, then you are doing the right thing. What *should* happen next is that the Windows upgrade tool automatically upgrades your existing legitimate, properly activated Windows 7 installation to a legitimate, properly activated Windows 10 installation (asks you a bunch of questions along the way).
More details:
How to upgrade to Windows 10 without waiting in line | The Verge
After that, you can burn yourself an ISO and re-install Windows 10 clean as often as you like, for the lifetime of the system (and by "lifetime", Microsoft means until you replace your motherboard, which has the license information stored in its ROM).
If this is what you did, and you're still experiencing problems, let us know what they are - and let's figure them out!