A beauty brand spends $32 to acquire a customer through Meta, sells them a $28 serum with 65% gross margin, and calls it a win because ROAS looked fine on the ads dashboard. It isn't a win yet. That customer hasn't paid back the acquisition cost, and until she does (through that order or the next one), the brand is carrying the loss. That gap, between spend and recovery, is the ecommerce analytics payback period for beauty, and it's the metric most founders check last when they should check it first.