Prevent users from sharing their login information

[sharmanaetor]

There are certain sites that have tutorials or other content of value and charge a membership fees. I was wondering what prevents users from buying membership on a site and then sharing their login info with friends/family or posting that information publicly online. That way, only one person actually buys the subscription but multiple people can gain access.

[Shalle]

1 session per account is pretty useful, that way it's less likely users will borrow their account to other people. IP restrictions is another soloution.

[sharmanaetor]

That's the only thing I could come up with as well.