Modify WooCommerce subscription start date without debug mode

woocommerce-subs-start-date-edit-debug-off

/* Add _subscription_start_date back to the viewable order meta data */
add_filter( 'woocommerce_hidden_order_itemmeta', 'theme_hide_order_itemmeta' );
function theme_hide_order_itemmeta( $hidden_meta_keys ) {
	if ( ! defined( 'WCS_DEBUG' ) || true !== WCS_DEBUG ) {
		if(($key = array_search('_subscription_start_date', $hidden_meta_keys)) !== false) {
		    unset($hidden_meta_keys[$key]);
		}
	}
	return $hidden_meta_keys;
}