Check the below settings: - Install the Google Play app (Market app) and check whether Google Play Services run on the device.
- Register the payment method for your account and run the market app at least one time to keep the latest version of the agreement on market use.
- The key store file from your test app and that from the signed APK which is registered on the Google Play Console should be the same.
- Upload your application to the alpha distribution channel in the Release management > App release, on the left menu of the Play Console page.
- Your Google account signed in on the device should be registered on the published version of the tester.
- Even you have registered your device account on the Google Console tester, make sure to opt in to the device account via test participation URL in the Release management.
After all settings complete, purchase is available to process in case device account issue does not exist. Check the all process of charge and refund for the actual purchase. If you want to examine on the sandbox without charging, you can input your test account in the Play Console Settings > Developer account > Details > License test. Its count is limited, so request GCP Platform Client Team when input is unavailable. Depending on the payment method on the device or account state, purchase may be restricted.
Reference: https://developer.android.com/google/play/billing/billing_testing.html?hl=ko | 