If you need to get some user meta, just add this to the file abstract-bewpi-invoice.php
public function display_tva()
{
$order = new WC_Order( $this->order->id );
$tva = get_user_meta($order->user_id, 'TVA');
echo 'TVA : '. $tva[0] .' <br/>';
}
Just replace ‘TVA’ by your meta_key.
Then, in your template body.php e.g add :
`<?php $this->display_tva(); ?>’