Hello everyone! 

The "Gift responsible" is the user who is in charge of the reward, so every time someone reaches the points needed to get it, Odoo will schedule an activity (Figure 1.0) to remind the "Gift responsible" to give it or do something about the reward.

Nevertheless, let's keep in mind that the referral rewards are not defined as products in Odoo (product.template/product.product), so you won't have an inventory tracking of your rewards. 

Depending on the business case, the gift responsible could be in charge of buying the reward and receiving it. Still, creating a product (product.template/product.product) to purchase and accept is needed. (Figure 2.0)

Note: the "Product Type" would depend on the business case. 

Disclaimer:

This is not an official documentation.