You're right, the site is TheGameKeys.com ... I often buy on sites like that, but first time i got a problem
And they dare to say it's legit :
I've contacted GOG about this, but i don't think this will be useful
Hello WesB,
If you used Paypal then you have up to 45 days after purchase to open a dispute. You can do that through your PayPal profile under the Resolution Center.
You don't have to worry since its 100% certain you will get you money back but just give PayPal 15 week days to investigate the dispute.