WPSEO_Features::is_free PHP Method

    public function is_free()
    {
        return !$this->is_premium();
    }

 /**
  * Initializes the banner sidebar by setting its banner spots.
  *
  * @param WPSEO_Features $features Class regarding WPSEO Features.
  */
 public function initialize(WPSEO_Features $features)
 {
     if ($features->is_free()) {
         $this->add_banner_spot($this->get_premium_spot());
     }
     $this->add_banner_spot($this->get_services_spot());
     $extensions_spot = $this->get_extensions_spot($this->get_active_extensions());
     if ($extensions_spot->has_banners()) {
         $this->add_banner_spot($extensions_spot);
     }
     $this->add_banner_spot($this->get_courses_spot());
     $this->add_banner_spot($this->get_remove_banner_spot());
 }