I run a boutique fitness studio that offers three distinct services—one-on-one personal training (circuit or reformer Pilates), semi-personal sessions for two clients, and a small “group” format that also caps at five. I’m ready to give members an easy way to buy and manage their packs of sessions directly on their phones. Here’s what I need the app to do: • Display all three session types—Personal Training, Semi-Personal, and Group—each with its own set of pack options. I already have the exact pack sizes and prices in mind and will supply those details once development begins. • Handle secure in-app purchasing so clients can pay, store, and track their remaining sessions. • Let users switch seamlessly between personal, semi, or group credits when booking, depending on which pack they hold. • Provide an admin back-end where I can load new offers, see sales, and monitor session redemptions. • Optional but desirable: simple calendar integration so clients can view availability and reserve a slot right after buying their pack. I’m open to the tech stack you recommend—native iOS/Android or a cross-platform framework such as Flutter or React Native—as long as purchases are smooth and the interface is clean. The key deliverables will be the live app (deployed to both app stores), source code, and a short hand-over guide so my team can manage packs and updates going forward. If you’ve built purchase-driven fitness or booking apps before, let’s talk.