One device burned through 14,178 free trials while my costs tripled

Our image generation bill basically tripled in 9 days. Installs were flat, revenue didn't move, no campaign, no launch. I spent two evenings staring at dashboards before it occurred to me to just ask. I had Claude dig through our cost logs and subscription data. The answer was immediate: one device made more generations than all our other users combined since early October. It cycled through 9 different Apple IDs, each starting a fresh 3-day trial, cancelling before converting. Never paid a cent. The problem was obvious in hindsight. Our trial limit checked per account, not per device. So every new Apple ID meant a fresh unlimited trial. And yes, unlimited on purpose. Our paywall and listing literally say unlimited generations, and quietly capping something you advertise as unlimited is the kind of thing that gets you rejected from app review and a wave of angry reviews. We're adding per-device caps now, but a lot of real families share one iPad and I don't want to block them. Per device, per payment method, a daily generation limit during trial—has anything actually worked for you without annoying normal users?