Problem with Android licensing service

I implemented Licensing Service in my application using the sample given with licensing module. I am using the standard ServerManagedPolicy. I have not changed anything in the policy and it actually works fine. I have following questions.

1. Sometimes, this happens randomly though, it says that application is not licensed and asks for buying it and then I try again it works fine. So few times, it will say, app is not licensed. I have seen this both on real phone and emulator. This is a serious concern, because if the user who buys the app later 开发者_运维知识库on see the popup that app is not licensed, he is gonna get irritated. May I please know what is wrong with the standard ServerManagedPolicy code.

2. For a paid app, is the standard ServerManagedPolicy implementation given in the sample code enough, or do you recommend to tweak it and add / modify some checks.

Implementing Market license checking API is a waist of time from my experience.

My game, Elastic World, got cracked a few hours after being on the market. There's an android application called Lucky Patcher that cracks any APK that uses Market licensing API.

In the implementation of market licensing, I did everything by the book, following all google's recommendations, but Lucky Patcher always cracked the protection. I spent a couple of days on this trying several approaches, different kinds of obfuscation, placing the validation code in other areas of execution, but nothing worked.

This sometimes happens when licensing is unable to access the market for validation.

There's an issue with the default SetValidityTimestamp code where the default VT value is returning null.

See this link for details and a fix. I've implemented this in my own apps and have not seen the issue since or had any market reports of it.