Subscription billing glossary
Quick definitions of the terms you'll encounter when building in-app purchases and subscription logic — from A to Z. Want the deep dive on any of these? Read the server-side purchase verification & entitlements guide.
Entitlement
A server-side record of whether a user should have access to a feature because of a verified purchase.
Purchase token
A unique opaque string issued by Google Play (or transaction ID by Apple) that identifies a single in-app purchase.
RTDN
Real-Time Developer Notifications — Google Cloud Pub/Sub push messages that tell your backend about subscription lifecycle events.
Server-side receipt validation
Verifying purchase data by calling the store's API from your backend — not from the client device.
StoreKit 2
Apple's modern in-app purchase framework with Swift-native APIs and JWS-signed transaction verification.
Google Play Billing
Google's billing library for selling digital products, subscriptions, and in-app items in Android apps.
MRR
Monthly Recurring Revenue — the predictable subscription income you can count on every month.
Churn
The rate at which subscribers cancel — usually measured monthly as a percentage of your active base.
ARPU
Average Revenue Per User — total revenue divided by the number of users over a given period.
LTV
Lifetime Value — the total revenue you can expect from a subscriber over their entire relationship with your app.
Paywall
A screen shown to users to convert them to a paid subscription — typically showing plan options with pricing.
Win-back
A discounted offer targeted at lapsed subscribers to bring them back to your paid plan.
MCP
Model Context Protocol — an open standard that lets AI agents interact with external tools, including subscription management.
MTR
Monthly Transaction Revenue — the gross in-app purchase revenue processed through a store before any deductions.
Grace Period
The entitled recovery window after a renewal payment fails.
Account Hold
Google Play’s suspended payment-recovery state after grace ends.
ARPPU
Average Revenue Per Paying User — revenue divided only by users who paid.
Free Trial
Store-managed subscription access before the first paid charge.
Introductory Offer
A free or discounted opening subscription phase for eligible customers.
Trial Conversion Rate
The share of trial starts that become successfully paid subscriptions.
Sandbox Testing
Testing store purchases and lifecycle events without real charges.
Service Account
A Google Cloud workload identity used by a backend to call Play APIs.
Purchase Acknowledgement
The required Play confirmation that a completed purchase was processed.
Billing Retry
Automatic store attempts to recover a failed subscription renewal.
Proration
How unused subscription value is applied during a plan replacement.
linkedPurchaseToken
The Play field connecting a replacement token to its predecessor.
App Store Server Notifications
Apple-signed webhooks for purchase and subscription lifecycle events.
Renewal
The recurring store charge that extends a subscription period.
Refund
A store-issued payment reversal that can change entitlement access.
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