Doesn't Humble Bundle also have legit keys too? (the witcher series)

Possibly. At any rate, it's a very small number of games and I don't believe they're for less than they are here.

Yes, number of digital retailers have been granded licence to sell GOG keys for Witcher series, but those are exception due to being developed by GOG's sister company CDP RED.

You also see legal GOG keys on occasional bundle but those are rare and far between. More of marketing stunts rather than anything else. Even Kickstarter projects have allegedly have difficulties getting GOG keys for their backers so some have opted giving Humble keys instead.

You seemed ok before, now acting like this because I mentioned an interesting fact in literally nothing other than a conversational tone?

As a general response;

-You don't have to be licensed to sell second hand goods, only saying you are a licensed reseller would be wrong

-You don't have to give details of return policies to sell anything unless it is prescribed as being required. Anything prescribed will need stating, and anything you do state is binding whether required or not, apart from that you don't have to give any details at all and consumer laws will govern what rights anyone has (up to the individual to know this)

-VAT is no issue, just works as normal. No special permits needed to sell second hand goods and no pawnbroker business is being conducted.

Just my thoughts on what you said, not whatever you seem to think is happening :/