Hi Garth,
To check if the meta box is registered only for admin, please check the PHP file that has the meta box code. You might want to check something similar to this:
add_action( 'admin_init', 'your_function' );
function your_function() {
add_filter( 'rwmb_meta_boxes', 'your_meta_boxes' );
}
// Or
if ( is_admin() ) {
include 'your-meta-boxes.php';
}
Regarding the purchase: yes, you only need the Frontend Submission extension.
