What is sandbox testing (TestFlight and license testers)?

Apple's sandbox works with development-signed apps and with TestFlight builds, which always run in the sandbox. You create Sandbox Apple Accounts in App Store Connect and sign in on the device. The settings let you change the subscription renewal rate, clear purchase history, which also makes the account eligible for introductory offers again, and simulate win-back offers. Apple also offers StoreKit testing in Xcode, which runs on a local configuration file with no network. Those transactions are signed by Xcode, not by Apple, so your server needs Xcode's certificate to accept them.

On Google Play you add license testers in Play Console. Testers see test payment methods, a notice on the purchase dialog, and no tax. Test subscriptions renew faster: 5 minutes for a week or a month, 10 for three months, 15 for six months and 30 for a year, with at most six renewals. A free trial lasts 3 minutes, a grace period 5 minutes and an account hold 10 minutes. A test purchase that your app does not acknowledge is refunded after 3 minutes. Play Billing Lab can move a test subscription into grace period or account hold.

RevenueDot takes the environment from the store, so these purchases are stored as sandbox. They grant entitlements, and webhooks carry environment: SANDBOX, but charts and metrics count production only unless you ask for sandbox. For quick tests with no store account, use the Test Store.

Sources: Apple: Testing Apple In-App Purchases with sandbox · Apple: Testing at all stages of development with Xcode and the sandbox · Android Developers: Test your Play Billing Library integration