Since I’m creating a free websites so i was thinking to implement chatbox and filesharing feature as I am creating it to present as a demo of a university owned social networking site by but they come for a cost I’m not willing to go for currently. so I guess i would be fine
Nope, account activity is solely based on website traffic. If you check your website once per month but never login to the control panel, your website can stay active forever.
But the other answers were correct: having a registration and login system on your site is no problem. Having people use your site for file hosting/sharing and live chats is not allowed, because they use way too much disk space, bandwidth, server power and so on.