Check whether the player bought a donation or not

How do I check if the person donated or not? I know that the donation should be done with the command Marketplace: but if I write if and this command, it does not work. I need to make if the player has donated, then give him 10k coins. How do I do this? Write if MarketPlace:
+10k

Or how?

I recommend checking out this explanation for developer products: Developer Products | Roblox Creator Documentation