Interesting idea, but two things struck me here:

1. Does that mean a student would have to pay to install it on their school computer? Or maybe a school provided laptop?

2. What about personal installs for other people? Not as a business or service, but merely on a friend or relative's computer?

Because in theory, both of those would come under 'someone else owning the machine', but they'd also be seen as personal usage by any rational person.