The wording in the license as of R2015b was that the Student Version license could only be installed in a single system at a time, and would have to be deactivated for transfer to a new machine. Transferring is permitted a small number of times per year. Also, an indefinite number of re-installations are permitted on the same host, as long as the host retains the same hardware that is keyed off of (the hard disk for MS Windows, an ethernet device for OS-X or Linux)
Some people, including Mathworks people, have said the Student version can be used on two systems simultaneously, but the license terms disagreed, at least in R2014a and R2015b.
I do not have a copy of the license terms for R2016a available to check.