Update Post Taxonomy Automatically Based On Date

You just need to set it up like this:

if ( ! wp_next_scheduled( 'check_event_status' ) ) {
  wp_schedule_event( time(), 'daily', 'check_event_status' );
}

add_action( 'check_event_status', 'set_event_status' );

install the Debug bar plugin and add the cron extension for it if You need some debuging info about the cron job and to be able to manually delete if needed.