# How it works

Time-based billing charges customers for **actual time** they spend with billable content rather than a flat membership fee. It fits streaming, reading, and listening experiences where value scales with engagement.

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## The core flow

The mental model is four steps:

1. The user **connects a payment method** through `tiun.start()` on your paywall.
2. tiun starts a **billing session** and begins **metering time** against your configured interval and price.
3. The user is **billed for time spent** according to the product's interval fee and optional monthly cap.
4. The session **ends** when the user leaves, your app stops billable content, or payment fails — access returns to the locked state.

You configure the product itself in the dashboard (interval, fee, monthly limit — see [Products](/reference/generic/products.md)). The SDK and events connect that configuration to your app's UI and routing.

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## Where the details live

The rest of the time-based reference is split across three pages, each owning one piece of the model:

* [Sessions](/reference/time-based/sessions.md) — the session lifecycle (Locked / Active / Ended), what tiun tracks behind the scenes, and the `sessionId` you can verify server-side.
* [Access](/reference/time-based/access.md) — the `paywallShow` and `paywallHide` events that tell your app when the user has access.
* [Protecting content](/reference/time-based/protecting-content.md) — how to gate the UI with paywall events and how to use `tiun.setContent()` to control metering as the user navigates.

For an end-to-end walkthrough, see [Build a time-based paywall](/guides/time-based-billing/build-a-time-based-paywall.md).


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