Lost Avast

Dear Sir/Madam,

I was having software problems with my PC so after many attempts at rectifying the problems we finally reset the PC to factory conditions.
In the process I lost my Avast Premium security for which i had paid, I think last August. Is there ay way that it can be restored without my having to pay all over again

Sure, see: https://support.avast.com/en-ww/article/Install-Activate-product/