title: In-app billing. How to store information that user has paid?
body: <p>There was a similar subject <a href="https://stackoverflow.com/questions/9462641/how-to-check-my-in-app-billing-product-is-already-purchased-in-app-by-user">here</a></p>
  
  <p>Okay. We can find out about user's purchase using RESTORE_TRANSACTIONS request to Google Play.
  But. It is written in documentation that
  " You should use the RESTORE_TRANSACTIONS request type only when your application is installed for the first time on a device or when your application has been removed from a device and reinstalled."
  Why not after every start? 
  It looks comfortable and possible to query Google Play every time when the app starts.</p>
  
  <p>Otherewise</p>
  
  <p>1) I should store information about payment on my WEB server</p>
  
  <p>2) Or I should save this info to sdcard. The record should be secure, including
  device ID, so that copy on another device will not work</p>
  
  <p>So. Which way is better?
  Thanks.</p>