In-app billing from Google Play Store can used for virtual game products, app functionality such as unlocking an ad-free version or version with advanced features, subscription services for things like streaming music, videos, books or other media, and cloud software products.
These guidelines say that developers must use Apple's in-app purchase function for things like unlocking app features or functionalities such as "subscriptions, in-game currencies, game levels, access to premium content, or unlocking a full version."
If you allow in-app purchases of the types specified by Google Play or the Apple iTunes App Store (in-game currencies, ad-free versions, subscriptions, etc.), you should mention this in your Terms and Conditions.
Let your users know that your in-app purchases will be done through Google or Apple, and that there are policies in place for both Play Store and App Store for these kind of in-app purchases.
Examples of in-app purchases clauses
Here are a few examples of how popular apps that allow in-app purchases include this information in their Terms and Conditions through in-app purchases clauses.
The WeatherBug app offers a purchase option that allows a user to disable all advertising by paying an annual fee.
Users are informed that "payments will be processed through the Google Play or iTunes app store from which you originally downloaded the application."
Users are also informed that they can access "the applicable "in-app" purchase rules and policies directly from the app stores."
Channel 4 games includes a thorough section on in-app purchases in its Terms and Conditions agreement.
Six sub-sections cover topics from managing the ability to complete in-app purchases, how to get a refund, and age limits to making purchases.
"More information about how you may be able to switch off and/or manage In-App Purchases using your device may be set out in the App Store Provider's terms and conditions/EULA."
"If you make any In-App Purchases in the Game, then the App Store Provider's terms and conditions/EULA applicable to In-App Purchases will also apply."
"In the unlikely event that we are unable to replace or repair the relevant In-App Purchase or are unable to do so within a reasonable period of time and without significant inconvenience to you, we will authorise the App Store Provider to refund you an amount up to the cost of the relevant In-App Purchase. Alternatively, if you wish to request a refund, you may do so by contacting the App Store Provider directly."
"You acknowledge and agree that all billing and transaction processes are handled by the App Store Provider from whose platform you downloaded the Game and are governed by the App Store Provider's terms and conditions/EULA. If you have any payment related issues with In-App Purchases, then you need to contact the App Store Provider directly."
Here is what the "In-app Purchases" clause looks like:
This thorough Terms and Conditions from the Channel 4 app makes it very clear to users that the "App Store Providers" - Google Play or App Store - are responsible for a significant portion of the in-app purchase transactions, including payments and refunds.
Calm offers purchases and subscriptions both directly and through an App Provider.
Users are informed in the Terms of Service agreement of Calm that they can cancel subscription renewals by emailing Calm, or by going through the App Provider if that's where they've made a purchase:
MLB.com lets its app users know that "In-app purchases are purchased from and billed by Apple iTunes, not MLB.com" and that "these purchases are subject to the terms and conditions of Apple iTunes."
If your app has in-app purchases that go through an app store, such as Apple App Store or Google Play Store, disclose this to your users in your Terms and Conditions agreement.
Let users know that they should check the app store's own Terms and Conditions agreement if there are any issues with their in-app purchase, and that the app store handles the billing - not you.