If you don't want to, none. As soon as you sign up you can discontinue your membership, and to go the extra measure mark the one email you will get from amazon student (confirmation email) as spam to make all future emails from them go to your spam box. The emails they do send you are special student deals so you can decide if you'd like to keep those. By discontinuing the membership you also lose the free 2 day shipping for 6 months but if you don't shop on amazon this doesn't matter.