In order to view both Invoices and your payment receipts, you will need to navigate to your account's Billing Details.
After an invoice has been paid, you will see an invoice for that month marked as "Paid" within your Twilio SendGrid UI.
To view the Invoice and the receipt for payment, you can click on any month and the invoice for that month will automatically download. Invoices are also emailed to the billing email address on file for your account every month.
The receipt portion of the invoice will be displayed once the invoice has been paid, and is located at the bottom of the invoice.
The Transaction Summary shows the total charges for the month, and the Payment Summary shows the payment type and last 4 digits of the card that was charged.
Additional assistance with reading your invoice can be found here - Reading Your Invoice.
If you have any questions about your invoices or payments, please open a Twilio SendGrid Support ticket and our team will be happy to assist you.