Server-to-server notification

Without server notifications, a publisher’s picture of its subscriber base is only as current as each person’s last session. A subscriber who cancelled six weeks ago and has not opened the app since is still, as far as the app knows, a subscriber.

Apple, Google, Roku, and Amazon all solve this the same way. When something happens to a subscription, the store posts a message to a URL the publisher registered: renewed, cancelled, refunded, entered billing retry, price consent granted, upgraded. The events arrive whether or not the subscriber is present, which makes them the only reliable source of truth for entitlement across a base that spans several stores, each with its own event names and its own delivery guarantees. Reconciling those vocabularies into one internal state is most of the integration work, and it is why receipt validation and notification handling get built together rather than separately.

The part that gets skipped is what happens next. A billing-retry event is not only a row to update, it is the trigger for the screen that subscriber should see at their next session start while access is still live. A refund event says something about the last thing that person was shown. A cancellation event dated three weeks before the app noticed is the difference between a win-back that lands and one that arrives after the subscriber has moved on. Treating each event as an input to the subscriber journey rather than as a billing record is what turns the integration from bookkeeping into something that changes outcomes, and the SDK is where that state reaches the surfaces the subscriber actually touches.