WP-Optimize Purge cache automatically when balance change

where can I add this code add_filter( 'mycred_add_finished', 'check_for_balance_change', 1000, 3 );function check_for_balance_change( $reply, $request, $mycred ) {if ( $reply === true ) { wpo_cache_flush(); } return $reply;} On WP-Optimize plugin