function wpf_only_allow_completed( $order_data, $order ) {

if ( 'completed' !== $order->get_status() && ! wpf_has_tag( 'Clienti - Ordine Completato - Identificazione Effettuata', $order->get_user_id() ) ) {
        return null;
    }

    return $order_data;

}

add_filter( 'wpf_woocommerce_customer_data', 'wpf_only_allow_completed', 10, 2 );