I don't think you can, looking at this link.
I know our student has to buy the latest version each year as this link states as it ceases to work after a year.
I could be wrong though as it could be different for different countries.
I would suggest contacting your local reseller to find out for sure.
what version is the instructor code for?
you will most likely need tho install the version he is using.
is it student or educational?