Confirm a purchase from the server-side

Hi.
I have a Unity game using in-app purchase.

After a user purchase a product the detail is sent to the server and the server must deliver the product to the client.

Is there a way to confirm a purchase and consume the consumable product for that client from the server-side?

Note: If I send the information back to the client and confirm the purchase at the client-side (to tell the apple that the product is delivered), the process would be complicated. (It would be about 7 steps based on the conditions of my application)

Confirm a purchase from the server-side
 
 
Q