title: Google Play Game Services unlock achievement - store unlock in game or call unlock() every time?
body: <p>I am developing an Android game which uses Google Play Game Services.</p>
  
  <p>When a player reach for example 10000 points an achievement gets unlocked.
  So when the player reaches 10000 points I call </p>
  
  <pre><code>Games.Achievements.unlock(...)
  </code></pre>
  
  <p>The question is what to do when the user reaches 10000 points again in another game. Do I have to check if this achievement is already unlocked or can I just call unlock() again?</p>
  
  <p>I know that the Play Services popup is diplayed only when the achievement gets first unlocked. But I am concerned about the quota of api calls. If I for example store the achievement unlock from shared preferences then I would do something like this:</p>
  
  <pre><code>if(myAchievementIsLocked){
     Games.Achievements.unlock(...)
  }
  </code></pre>
  
  <p>What are the best practices? I was looking at some samples but didn't find the answers which I was looking for.</p>