Hello,
What it sounds like you saw at the end of the activation process is simply a generic "Thank You" message that has no relevance to how or where you obtained the license.
As you are a student, I'm assuming that your serial number was acquired through the Autodesk Education Community (http://students.autodesk.com/), which is free for registered users, providing 3 year termed licenses for available products and releases.
If you have any other concerns, please PM me your serial number so that I can look it up in our system. Otherwise, if this reply was helpful, please click "Accept as Solution".