title: How to check my In-app billing product is already purchased in app by user?
body: <p>i need to check when app start then the In-App product is already purchase by user or not.</p>
  
  <p>how to check user is already purchase specify app product ?</p>
  
  <p>its also working when app uninstall and re-install app , this functionality provide by android api or not ?</p>
  
  <p>can anyone suggest me which step follow for this so user not again purchased product and we check in app side its purchased then we give some features to users in app..</p>
  
  <p>Thanks</p>