Let’s look at an example of how it actually works:
In the Stock Rewards Pocket, you choose any stock or ETF you like. For instance, you choose stock "A".
You purchase something for 100€ with 10% cashback. Thus, we refund you 10€.
Cashback will be received in your Stock Rewards Pocket as a fraction of the "A" company share. Let's assume that the "A" stock has a price of 100€ at that moment. That means you will receive 0.1 of "A’s" company share in your Reward Pocket.
After some time, the price of the "A" stock rises to 110€. Your reward in the pocket would be 0.1 stock * 110€ = 11€ at this moment.
Then the price of "A" stock becomes 105€. Your reward would be equal to 10.5€.
Later if the price for that stock decreases to 90€, your reward would be 10€. Moreover, if the "A" share price becomes 0€, your reward would still be 10€.