Last day of renewal today- I have to add 1 more PC but can't figure out how

Hi, my avast! Internet Security (1 PC, 1 year) ($49) is expiring today (alert says I only have 1 day left), I want to renew but I need protection for 2 PCs. I can’t change the QTY field in my cart. I can probably purchase it separately but I fear that the discount will not be applied if I go that route.

Avast Internet Security is normally for 3 systems, unless you originally purchase a ‘single’ PC license ?
So if you purchased outside of the avastUI, renewal it would probably be a 3 system license, that in itself might be cheaper than purchasing two licenses,

So does the cart or the previous screen show how many systems this can be used for ?