All payments and invoicing are handled by MyCommerce / ShareIt. MyCommerce is the seller on record, and they are issuing invoices. When you complete the purchase, you will get an email from MyCommenrce containing the invoice, and it is important to keep these emails safe or download the invoice for your archive. And later, you can download the invoice from your account at MyCommerce. To log in to your MyCommerce account, check out this article.