Ever thought of um updating? The license is valid and i can't think of a single reason to stay with old 4.8 these days. Especially since version 5.0 offers superior performance, protection with brand new scan engine and new features along with much better interface. I've moved to it right on its release and never looked back.
Besides, avast! 4.8 will be soon discontinued, probably at the beginning of next year. So, you'll have to update it soon anyway. But why wait if you can have new tech today?