Add custom value to custom column in shop_order post type

functions.php

<?php
/**
 * Add custom value to custom column in admin on page that lists the shop_order post type.
 *
 * @param string $column This is the column id/key.
 */
function add_custom_column_value_to_shop_order( $column ) {
	global $post;

	if ( $column == 'software_key' ) {
		echo null !== get_post_meta( $post->ID, 'software_key' ) ? get_post_meta( $post->ID, 'software_key', true ) : '-';
	}
}

add_action( 'manage_shop_order_posts_custom_column', 'add_custom_column_value_to_shop_order' );