What do you get with Pro compared to the Home Free edition? Is it worth paying for? We always feel a bit guilty when useing free software and if there is something extra with Pro we would prefer to pay. We are using the free edition at the moment.
Avast Home V Avast Pro differences http://www.avast.com/eng/av4_version_comp.html
You have to decide if the differences and additional flexibility, scheduled scans, automated actions, script blocker, enhanced user interface, etc. are worthwhile to you, enough to purchase, many people do.