for IAP should store.availableStores.apple & store.isActive checks before regularly in "enterScene"?

for IAP should store.availableStores.apple & store.isActive checks be performed regularly?  For example in a Storyboard “enterScene” as opposed to “createScene”?

that is could it be possible to get a fail in one of these checks, after which the user could correct (E.g. loggining onto their iTunes account), and then upon retry the checks should pass?  If so then I assume these checks should be performed regularly (i.e. even every time a purchase attempt is made) to cover off this possibility no?

I only check them before I make a store.* request.  For instance, I check them before I show buttons on a scene that allows purchases or restores.  I check it before I call store.init().  

As for store.avalableStores.apple, probably not much of a need to check that more than once.  Either your app is built for Apple or not.  Is active you might want to check more frequently but you really only need to check it when it’s important.

I only check them before I make a store.* request.  For instance, I check them before I show buttons on a scene that allows purchases or restores.  I check it before I call store.init().  

As for store.avalableStores.apple, probably not much of a need to check that more than once.  Either your app is built for Apple or not.  Is active you might want to check more frequently but you really only need to check it when it’s important.