title: Unlocking trial application by in-app billing
body: <p>I'm going to publish one commercial application on Google.Play. 
  I have idea to create <strong>only one version</strong>. It's free to use during 2 weeks after installation (trial period). After expiring of trial period user will have dialog with suggestion to buy <strong>full lifetime license</strong> of application throw the <strong>standard in-app billing</strong> (Google.Play purchase for managed product).</p>
  
  <p>I have no experience with Google.Play production. The questions for more skilled guys:</p>
  
  <ol>
  <li>Is it proper way to do such things? I mean unlocking free trial app using in-app purchase.</li>
  <li>Is it easy to restore transaction after reinstallation of application/changing devise? Do I need to save some information about transaction on my web server or something?</li>
  <li>Does anyone have some experience in this way?</li>
  </ol>
  
  <p>Thanks for your help!</p>