Once again I’m getting an Avast alert that my protection is running out of its trial period. Avast has only been installed about one month, I thought I had 14 months on the free trial. How can I defeat this nag screen? ???
The trial period is 60 days. If the version you are to be using is Avast Home (free) registration is required to continue receiving updates beyond 60 days. This registration is straightforward, and needs to be repeated yearly, which I find isn’t a problem. See here: http://forum.avast.com/index.php?topic=30209.0
buy the full version (Pro) 
Look, you won’t receive program & virus database updates while you keep the trial version. Buy the Pro or register the Home version.