There are strict regulations, set out by the Department of Justice, regarding the class attendance of non-EU students. 

It is an offence to:

Scan your card and then not attend the lecture.

Scan someone else's card. 

DBS regularly carries out spot checks on classes to ensure that these instances do not occur. If any such instances are identified all students involved are called to a disciplinary meeting, with potential sanctions up to and including expulsion from the College.