How many machines can I install my SPSS Grad Pack on?

How many machines can I install my SPSS Grad Pack on?
Students are permitted to install the SPSS Grad Pack twice during the license term on their personal machine. It is recommended you only install it on one machine at a time, in order to preserve your second installation as a back-up. If you require it installed on more than two machines, you will need to buy a second license.