Purchased a license for the program sometime last year, but it doesn’t work and I’m finally getting around to dealing with it instead of letting it sit all this time like I have been doing. I just want to make sure that I’m not charged for it again when the next billing cycle rolls around (it’s on auto-renew), seeing as I can’t use it.
Welcome to the forum. 
See if this takes care of your concerns:
https://support.avast.com/Tickets/Submit/RenderForm/27/&cls02&ptf01&lic01&scr06
Choose your language and submit your problem directly to Avast.
https://www.avast.com/find-order
You can disable the auto-renewal there.