Can I be banned if I buy games from eneba.com?

Can you then be banned on ps4? And is that serious

Well, you can't be banned because they don't know where you got the download code from

Eneba is a completely normal sales site for games. This is not fraud in any way - so you have nothing to fear.

You don't need to hide anything, as only real (unused) keys are traded and this is officially a sales platform for game keys that is absolutely legal, such as Steam.