Today I got a notification that an out of stock item had been ended
(this is correct because I've hung onto it for the 180 days incase I wanted to reuse it).
However I noticed in my payments that I got a credit of 8c (which is the 2nd category upgrade monthly charge).
So it appears that if one has item upgrades like I do, they continue to be charged when the item count is zero and one hasn't yet ended the item yet.
This upon reflection makes sense, but I'd never thought of it before.
It will compel me to keep my 0 quantity items cleaned up as other wise I'm paying the upgraded item fees each month until I zap them (or the 180 days passes).
So I'm passing this along incase others use both upgrades and the "out of stock" option too.