How to upgrade from 10 Home to 10 Pro?

How do you do that?
Upgrade Windows 10 Home to Windows 10 Pro | Tutorials
- from the tutorial section.

Like anything else, caveat emptor, especially where the emptor (you) is being offered something that looks very good value.

I would add that quite a few of our new members join up here as they have issues with a recently installed copy of the OS, and a high proportion of those are due to bad keys purchased in good faith from eBay or other online "bargain" vendors.

Agreed, they look convincing ads, including the links to those users who comment.

Where could the hundreds of unwanted licenses come from? Are they somehow using a tool to generate them?

Well, you won't lose much as they are under £5 ...

dictum said:

The strange thing is, these vendors have very high ratings, like 99+% So the rate of dissatisfaction seems to be very low.

Yes it's quite easy to do, you just get some people to invent email addresses and give five star reviews, because of this scam the sellers like eBay added a "Verified purchase" so that the reviewer had to be an actual purchaser, - OK so you get a few false members, ( disposable emails and fake addresses ), to purchase the item and then give the review.

The fake sources do get closed down regularly by Ebay Etc but by the time this has happened they have made their profits and a lot of scammed users will not even bother to complain as the feel they have been duped, and are too embarrassed to complain