Yeah, basically what matthewarkin said. You could theoretically do it either way: (a) an app could say "Sell your product with us and we'll take 2%" or a seller

Yeah, basically what matthewarkin said. You could theoretically do it either way: (a) an app could say "Sell your product with us and we'll take 2%" or a seller can say (b) "I'm willing to give 1% of GMV to apps who list our products"