Hi I'm an italian student. I Downloaded Autocad 2011 as a student and as a free program and i get my product key and serial number. The 30 days to try autocad are done so i click on activation (not on buy license), then i fit the information about my adress and name. At the end of the procedure the program said "Thank you for buying a license". Does it mean i have to pay? I thought it was free, i didn't get any contract and i didn't give any information on credit card or payment. Please help me.
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".