If i make a game in Unity where a player can host their own servers, will it still cost me more money?

I know that with Unity’s networking system, you will have to pay Unity if you have more than X players on your servers at the same time. I believe this is because that Unity is hosting the servers, and it costs them internet service? But if the players are hosting their own servers, this wouldn’t cost Unity any internet. Is it possible to host your own servers using Unity networking, and if so, will it still cost extra money? thanks. :]