Italian VAT tax laws differentiates between an invoice and a receipt. All transactions must have a receipt, which only proves the payment and the receipt of the payment, but the invoice has much more information, some of which is mandatory, like customer name, customer fiscal code or Tax ID, customer address, customer email, goods or services received. If the customer of that service were an Italian tax person which later utilizes that invoice to deduct the paid VAT amount from their VAT tax due or from income tax statement, then that customer will request an invoice, not just a receipt. While the receipt is mandatory, an invoice is issued only to customers who request it, usually for the reasons above. An electronic copy of the same is also sent automatically to the Italian Revenue Service for cross check. In your case, I doubt you would need an invoice. If you request an invoice, then the invoice would be in lieu of the receipt, therefore the invoice would suffice the compliance of tax laws on the part of the entity providing the service.
