Are you supposed to SetAsync right after a player buys a developer product?

So Im having a lot of trouble with developer product and I was wondering right after the player buys something if I should use SetAsync right away ?

For Example if someone in your game buys a [1000 Currency] Developer Product Do I use SetAsync?

No, you only want to use SetAsync on PlayerRemoving, BindToClose and when autosaving. I'd even recommend you to use UpdateAsync instead of SetAsync. https://developer.roblox.com/en-us/articles/Saving-Player-Data