Acrobat 9 - Acrobat 11

I bought Acrobat 9 (disk from official re-seller) some years ago, and later I bought the updated version Acrobat 11 - on line because it was the way I have been told to do it. I never get any disk. When I bought a new computer,  I re-installed Acrobat 9 from the disk because it was the only version I had. But later I was not able to get back version 11 that I bought before. What do I have to do get back my Acrobat version 11? Thank you. Michel