| AcknowledgeResponseListener | A callback class that serves as a listener for monitoring the acknowledgement operation of a Purchase. |
| AptoideAccountStateListener | A callback class that serves as a listener for changes to the user's Aptoide account sign-in state. |
| AptoideBillingClientStateListener | A callback class that serves as a listener for monitoring the SDK setup process and the connection status with the Billing Service. |
| AptoideSignInResponseListener | A callback class that serves as a listener for the result of an Aptoide account sign-in operation. |
| ConsumeResponseListener | A callback class that serves as a listener for monitoring the consumption operation of a Purchases. |
| ProductDetailsResponseListener | A callback class that serves as a listener for the querying of Products. |
| PurchasesResponseListener | A callback class that serves as a listener for the query of Purchases made with the AptoideBillingClient. |
| PurchasesUpdatedListener | A callback class that serves as a listener for the Purchases made with the AptoideBillingClient. |