This is where the manyfold revenue streams of Facebook Credits become apparent, and they all have in common this observation: if you give Facebook users a few free Credits with the block of Credits they buy (at Target, online, and soon anywhere), they will spend all of those Credits and then want to purchase more. Rather than a straightforward discount, the new math of Facebook Credits means that consumers will never quite be sure if they’re getting a discount or cash back or more for less. Kind of like frequent flier miles where we’re never quite sure what the conversion rate is. Or eBay auctions where we “win” the ability to spend money.