Version 1:
Have a popup with two calls to action: one goes to the next item. The header of the popup would include the item name.
The other transmits on a channel to a popup with two options:
One transmits on a channel to a vending machine (takes 1 of the item) which updates the unique property for the item (using a channel and a counter). (add 1)
The second transmits on a channel to a checker, which checks if the property for the item is greater than 0.
If yes, it will broadcast a message to a counter that decrements the property of the item.
Using the same channel, it will grant that item.
Surprise! You need make this entire system for every item you need to be able to store.
(yes you can also make this system with buttons instead of popups, or simplify it to store only 1 item at a time by removing the property/checker)
Version 2:
Give the player a room where they can drop items to pick them up later.