ApphudSDK-Android
· Apphud Android SDK is a lightweight open-source library to manage auto-renewable subscriptions and other in-app purchases in your Android app. No backend required.
Download JD-GUI to open JAR file and explore Java source code file (.class .java)
Click menu "File → Open File..." or just drag-and-drop the JAR file in the JD-GUI window ApphudSDK-Android-2.0.0.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.