Mobile growth & monetization engineering. Computer Scientist at Adobe Acrobat Android (1B+ installs, 95M+ MAU). Writing about mobile payments architecture, subscriptions, and Android DevEx.https://rishabhships.com/https://rishabhships.com/blog/cross-grade-12x12/https://rishabhships.com/blog/cross-grade-12x12/Single-product subscriptions are a state machine. Multi-product subscriptions are a state machine sitting on top of a matrix. Here's the design, and the operational discipline that goes with it.Sun, 14 Jun 2026 00:00:00 GMThttps://rishabhships.com/blog/subscription-state-machine/https://rishabhships.com/blog/subscription-state-machine/Subscription state in a Play Billing app isn't a single source of truth. It's a derived view. Here's how I model it explicitly, and the small Kotlin library I extracted from doing this at scale.Thu, 11 Jun 2026 00:00:00 GMT