Multiple Computer for Home License Use.

Why is there a limit if you can only run on one computer at a time?

I have multiple computers with various OS's that I would like to have Matlab on; Windows 7 (2 computers), Linux (Ubuntu), and Mac. I am the only user in my house but would like to learn more subtleties on the different OS's.

Is there a way to have a single home for multiple platforms without having to choose which computers I want to install Matlab on?

Thank you, Matt