Help!!!!!!

Hiya, last year a friend downloaded avast free edition on to my pc but failed to tell me that you have to re-register every year! I have never recieved an e-mail telling me that i have to register again so im not really sure what to do.
At the moment i have avast 4.8 installed.
Im new to this computer malarkey and need someone to tell me what to do! Please feel free to e-mail me if you need to know anything else!
Thankyou XX

Register your free product http://www.avast.com/eng/home-registration.php

How to insert activation key http://www.avast.com/files/tutorials/insert_key.htm

avast! 4 FAQs http://www.avast.com/eng/faq-avast-4-home-professional.html

avast! User Guides and Manuals http://www.avast.com/eng/download-user-guides-and-manual.html

You are normally notified by a pop-up notification (not email) 21 days before you need to re-register. Also it is every 14 months, you can check the updates expiration date using the about avast (right click the avast ‘a’ icon).