Not able to modify number of days

// Filter to modify number of days of history to 180days. Default is 60 days.
add_filter(
    "simple_history/db_purge_days_interval", 
    function( $days ) {
      $days = 180;
      return $days;
    }
  );

Hello, I added the above code in functions.php file but it doesn’t seem to work. It does nothing. It doesn’t showed 180 days option in dates select box on this page -> ?page=simple_history_page

Thanks,