I’d like to accept “sticky posts/listings”. I’ve set up my GC
account and input my data into the plugin Admin Options. But in
testing, I’m still not prompted for payment. Is this a paid only
option?
The sticky listings require that you have payments turned on. If payments are not turned on the sticky listings will not work. The idea behind the sticky listings was to provide a “featured” level for paid listings. So the upgrade button will only be visible on to users who have a paid listing.