How can I pass the ID of a specific item from my database collection alongside the Wix Pricing Plans payment data?

Question:
"I’m using Wix Pricing Plans and need to pass an item ID from my collection to my backend onOrderPurchased function. What’s the best way to do this? I can make a temporary collection to save the userID with the itemID and then use the buyer ID to find the itemID but that is difficult the maintain and delete etc.

Product:
Wix Editor

What are you trying to achieve:
I want to pass data from front end session storage and use it in my OnOrderPurchased Function.

What have you already tried:
Already tried to use a collection connecting userID with the ItemID but difficult to maintain.

Additional information: