Hi Adrian,
Personally purchased or licensed software must not be installed on College owned systems and vice versa - thus if college funds purchase the license then it can only be installed on a College owned system - this rule applies for all software.
I am pretty sure that there are exceptions. Specifically I believe there are for Norton antivirus and as part of the Microsoft chest agreement for office.
Given that Wolfram are claiming the illegal use was perpetrated by machines which fall into both College owned and personally owned systems then I foresee further issues if someone uses a personally licensed copy of Mathematica from a personal system whilst on the College network and there is no College license in place!
I think in that case we would have to find the person and be able to prove that they have a personal license - although Wolfram are such ***** that I wouldn't put anything past them and the lawyers at mLaw. All the best, david