Grey market key seller? Yes you can get your key banned and maybe get your account in trouble on whichever platform (Steam, Origin, etc) you use.
They sell cheap because they get them illegitimately. Leaked press keys, keys bought with stolen credit cards, keys scammed from developers, datamined keys...
What all of these sources have in common is that the actual developer gets nothing at best, and a chargeback fee at worst. All your money goes to middle men.
So sure of yourself on how they get their keys because you’ve been brainwashed. I have bought literally hundreds of these over the years. 90% of the time it’s just steam region pricing working in the sellers favor. I have never had a key banned or an issue with my account for ten plus years now.
Your comment starts off quite condescending. That's not a very nice way to start a discussion. Therefor I am giving you a downvote today. Please try to be nicer in the future.
I'm not familiar with the site, but if it really is a scam as people are saying, we shouldn't be downvoting the question. We should be getting the word out that they should not be used.
Here are alternative known good sellers that also offer great discounts:
Humble Bundle
Green Man Gaming
Fanatical
Game Billet
There are others that are legitimate.
Avoid places like the site you listed, and also these ones especially:
G2A
Kinguin
If you buy from Eneba, G2A, Kinguin, etc. you may be fine. However, there’s risk that you may not be fine and have a key that was purchased via a scam or stolen credit card. Then that game which is linked to you can be deactivated from your Steam account, possible Steam account ban, etc. Don’t buy from them because you just don’t know where that key may have come from.
Yeah, it's possible. It's not incredibly likely, though, I've bought maybe six or seven games from key sites like that over the years and I've not been banned.
Just keep in mind that if the price is too good to be true it probably is- be really wary of any keys that are below the historical low for whatever game you're buying.
I use them all the time to get games on Xbox. I recommend using Paypal to purchase as I've run into issues when using card, but aside from that it's been pretty smooth. Haven't gotten any bans or anything like that.