The question is...what is the license that you paid for? That is what you should be downloading. The link I sent you is for all the download versions and you can pick the one you have the license for.
You will need to uninstall the Free version if that is what you have on your machine now.
1. Save a copy of Avast 6.0.1000 and save it to your HDD:
http://www.avast.com/download-software – all versions
2. Download the Avast Uninstall Utility
http://files.avast.com/files/eng/aswclear6.exe and save it to your HDD (it has uninstall tools for all Avast versions and products).
3. Disconnect from the Internet at this time.
4. Go to Control Panel and uninstall Avast through Add/Remove Programs if possible and reboot.
5. If Step 4 fails, boot into
Safe Mode (hit F8 repeatedly) and run the Avast Uninstall Tool.
Uninstall all prior versions and products of Avast at this time.
6.
Reboot.
7. Install the newest version of Avast and
reboot.
8. Get Internet access and register your copy or add the license key for Pro.
9. Update the Avast definitions.
Let us know if you have any questions. Thank you.