/**
  * Get purchased plugins
  *
  * @return array Plugin slugs
  */
 public static function get_purchased()
 {
     // This should be cached in a transient
     if (self::$purchased === false) {
         $purchased = Sputnik_API::get_purchased();
         self::$purchased = $purchased['body'];
     }
     return self::$purchased;
 }