@michaellautman– This is an interesting idea. We will think about putting it in future versions of Piklist.

For now, you can just use some standard WordPress code and the Piklist admin-notice partial.

Add this to your main plugin file or your theme’s functions.php. This does not go in the field file.

function my_validation_success()
{
 if (isset($_GET['message']))
 {
    $field_to_validate = get_post_meta(get_the_id(), 'YOUR-FIELD-NAME', true);

    if(!empty($field_to_validate))
    {
      piklist('shared/admin-notice', array(
        'type' => 'updated'
        ,'notices' => 'License validation successful'
      ));
    }
  }
}
add_action('admin_notices', 'my_validation_success');

I’m using $_GET[‘message’] to determine if the post is updated, but you can probably find a better way.

Let me know if this works for you.