If each person created their account at the college they'd be permanently linked, and only three basic accounts would be able to be created, if someone else tried to make an account after that, they'd be denied. It wouldn't matter if all three belonged fo different people, a fourth+ couldn't be made, unless one of the existing three linked accounts was premium.
It would be both very simple and sometimes a little difficult to determine if the accounts under the IP adress are the same person or not, especially since using different emails doesn't really prove or disprove anything as it's very easy to create and use multiple email addresses, but if they are the same person it's always eventually found out based on their behavior, actions towards things, the way they say things, other numerous circumstances, etc.
Winter Month: 2 
Night 
Blizzard Moon: 
