As Tech asked, why don’t you want to update to v2014?
To “downgrade” to less protection…
- Download and save http://files.avast.com/iavs9x/avastclear.exe
- Download and save http://filehippo.com/download_avast_antivirus/15860/
- Run uninstaller from step #1 (you will be prompted to run in safe mode, do so)
- Reboot
- Install v8.0 from step #2
- Reboot
- Insert license key and reboot again.
edit: Before inserting license make sure the program auto-update is set to “manual”.