Only the first year is discounted and then you pay the regular student price.
Many people seem to be overlooking the fine print when they sign up to the Cloud
First bullet point:
Eligible students 13 and older and teachers can purchase an annual membership to Adobe® Creative Cloud™ for a reduced price of US$239.88 for the first year. After the first year we will renew your contract automatically for another year at the then-current standard annual price unless you cancel"