What is In-App Purchase (IAP)? Complete Guide for 2026

How in-app purchases work

An in-app purchase is any payment a user makes inside an app. Most digital goods on iOS and Android go through Apple's or Google's billing systems, which take a commission and handle the payment. Physical goods and services, like food delivery or ride hailing, use the app's own checkout.

There are four broad types:

• Consumables: coins, credits and boosts that are used up and bought again.
• Non-consumables: a one-time purchase, such as removing ads or buying a level pack.
• Auto-renewable subscriptions: recurring access billed weekly, monthly or yearly.
• Non-renewing subscriptions: time-limited access that does not renew on its own.

Attributing purchase revenue

For a growth team, a purchase matters because of where the buyer came from. The flow is:

1. The user installs from a campaign and the MMP attributes the install.
2. The user buys something. The app or your backend sends a purchase event with the amount and currency.
3. The MMP links the event to the install and credits the revenue to the campaign.

A worked example: a campaign drives 4,000 installs at $1.50 CPI, so spend is $6,000. By day 7, 160 of those users have bought something for a combined $4,800. D7 ROAS is 4,800 / 6,000 = 0.8x, paying user share is 4%, and ARPPU is $30.

Getting purchase tracking right

• Send currency with every purchase. Mixed currencies without codes turn reports into nonsense.
• Track from the server when you can. Sending the event after receipt validation keeps out failed and fraudulent purchases.
• Avoid double counting. Fire the event once per transaction, keyed on the transaction ID.
• Handle refunds. Decide whether refunds reduce attributed revenue, and apply it consistently.
• Send value to ad networks. Purchase postbacks with revenue let Meta and Google optimize toward buyers, not just installs.

In-app purchases in Linkrunner

Linkrunner tracks in-app purchases with currency through its SDKs or the server-side revenue API, and subscription events through the RevenueCat integration. Revenue is attributed to the campaign, ad set, creative and keyword that drove the install and appears at D0, D3, D7 and D30 next to synced spend. Revenue events can also be mapped to network postbacks so ad platforms optimize toward purchases. See ROAS measurement for the full view.