So the avast popup is telling you you have 285 days left - which in itself is a bit strange as the first renewal reminder you get is 60 days (I believe) and from 30 days left the Subscription section changes to allow for renewal of subscription.
I suspect that there might be some out of sync action going on, something reporting you need to renew, when that doesn't match the actual number of days left.
Try a repair of avast:
XP - Add Remove programs, select 'avast! Anti-Virus,' click the Change/Remove button and select Repair, click next and follow.
Vista, win7 or later - Control Panel, Programs & Features, uninstall a program, select 'avast! Anti-Virus,' click the Uninstall/Change and select Repair, click next and follow.
You may need to/should reboot after the repair.