I was use “Restore In-App Purchase” blueprint-node.
In my case consumable “One-time products” is used. I pass into “Consumable Product Flags” input pin an array with identifys of all available consumable products. I call this node one time, after launch my app. If before previous closing was begining purchase and it was complited after closing, then this first call of that node will return information about that purchase.
If use non consumable products, then “Restore In-App Purchase” will return all that buyed purchase anytime calls (not first call only).
I did not find full documentation about “Restore In-App Purchase” node and find solution experimentally. I hope my theory is true 