/**
  * Return instance of self
  */
 public static function get($instantiated_by_premium = false)
 {
     // Instantiate self only once
     if (is_null(self::$instance)) {
         self::$instantiated_by_premium = $instantiated_by_premium;
         self::$instance = new self();
         self::$instance->init();
     }
     return self::$instance;
 }