Avast issues

On my Wifes Acer comp { Windows 7 } we have Avast free anti virus , have been satisfied for a couple yrs now .
For the past week she somehow got the paid version loaded but we haven't paid avast .
The program won't let us open or do anything w/o buying their full version .
Any ideas ?
Thanks
highpockets1

P.s
I tried system restore - nada
Tried to uninstall - nada
contacted avast - nada