Here's the situation: I have an old computer that came with Windows 7 Home Premium when I bought it. It has a product key sticker on it. Several years later I upgraded it to Windows 10 Home when Microsoft began offering free Windows 10 upgrades. Then some months later I had to upgrade to Windows 10 Pro to continue to work. So I went to Activation settings > "Go to Store" > entered my Microsoft account and credit card info and purchased the Pro upgrade. The purchase button changed to Start upgrade. I went through the upgrade process and now I have Pro installed.
My question is: if I want to reinstall Windows 10 Pro operating system from scratch(without using Reset PC or Refresh PC, just please ignore this option for now) what will I do when prompted for license during reinstallation/activation phase?
Because I've never received any media(CD/DVD/USB/Download URL) from Microsoft when upgrading from 7 Home Premium to 10 Home to 10 Pro nor did I see any product keys from Microsoft for 10 Home or 10 Pro. The only thing I received was the order history on my Microsoft account that has the order number, date of purchase and the amount I paid for Windows 10 Pro upgrade.
I called Microsoft(they passed me around 6-7 times no joke, they dropped my call on 5th transfer) and this is what they basically said in summary:
First rep said: If I want to reinstall from scratch I have to start from Windows 7 Home Premium, then upgrade to 10 Home(which was free but isn't anymore), then again up to Windows 10 Pro(using my purchased license I've never seen). Which means, they said, I have to buy Windows 10 Home now to be able to reinstall from scratch. I can't burn ISO of Windows 10 Pro to a media and install it right away because they said it's an "upgrade key" not full retail license of Windows 10 Pro.
Other rep said: my Windows 7 Home Premium key has been upgraded to Windows 10 Pro key, and that I can use that key on the sticker on my computer to install Windows 10 Pro from scratch via burned ISO on a media.
Their accounts and billing said in response to #1 that they won't refund me any money even though I want to purchase the full Pro version afterwards because 30 days have passed since the purchase. I understand all of that and accept it.
I'm a little confused. Could anyone confirm what are my options at this point based on your own experience with something like that?