Concerned from what I seen on BF phone

My boyfriend has an app named “FOAP” & from my understanding you sell your photos... I’m curious why he has it but I don’t want to seem “crazy”. I’m more so curious why he has that? Is he selling dick pics! Lol anybody ever hear of this? Should i be worried ? He posted a pic of HIMSELF AND GOT 3.8 rating I’m not sure what this is