Hello, in the game we made, we used free and some paid models from the unreal market. We plan to publish our game on Steam for a fee in the near future. Are the models we use subject to copyright? Will we have any problems?
We will publish our game on Epic Games later.
Stuff you buy on the marketplace is for you to use, in your game.
Just don’t do something like use Epic characters, and use their names 
So, after earning 1,000,000 million dollars for unreal and epic games, should I pay royalties? (The game will only be released on Steam for now)
Yes, you still have to pay Epic when you reach $1m, but that’s nothing to do with marketplace, that just related to profits.
I understand that the model packs I will use will not cause any problems, for now I will only release them on Steam and later on Epic Games. thanks
As long as the seller has the rights to the model he sells to you, the Marketplace grants you the rights to use it. If the seller doesn’t have the rights, the Marketplace can’t grant you because they don’t own it and you’re still subject to legal process from the true owner of the model. Some recent cases of this have been posted.
It’s good, but what’s the point if we can use the products on the marketplace in our games and not be able to sell our games?