title: how to make a key for unlocking premium features for app
body: <p>I tried to implement a "pro key" for my android app to unlock features which should be locked at "trail version" (the same app without the key)... </p>
  
  <p>I found some ideas and some explained code (e.g. <a href="http://www.yoki.org/2010/07/31/creating-a-freepaid-app-pair-for-the-android-market/" rel="nofollow">this</a>), but if I test this stuff it wouldnt do any thing. My app doesnt recognize the "package". </p>
  
  <p>The in-app-billing solution by google is much to complicated for me. I read the documentary a lot of times but it looks so weird to me. puhhh. :-/</p>
  
  <p>Oh man... I spent so many days and weeks for my app and now the release is the most frustrating task to do. </p>
  
  <p>I hope somebody could help me. </p>
  
  <p>Best wishes from Germany
  Martin</p>
  
  <p>Edit:
  I try to implement this in my SharedPreferences like this way:</p>
  
  <pre><code>if (isProInstalled(this)) {
          addPreferencesFromResource(R.xml.settingsactivity);
          PreferenceManager.setDefaultValues(SettingsActivity.this,
                  R.xml.settingsactivity, false);
          for (int i = 0; i &lt; getPreferenceScreen().getPreferenceCount(); i++) {
              initSummary(getPreferenceScreen().getPreference(i));
          }
      } else {
          addPreferencesFromResource(R.xml.settingsactivity_pro);
          PreferenceManager.setDefaultValues(SettingsActivity.this,
                  R.xml.settingsactivity_pro, false);
          for (int i = 0; i &lt; getPreferenceScreen().getPreferenceCount(); i++) {
              initSummary(getPreferenceScreen().getPreference(i));
          }
      }
  }
  </code></pre>