When an invoice is sent to a customer you will receive a copy to your designated email, you can also view and download any of your invoices.
In Invoicing, there are drop-down menus to filter invoices based on their status (paid, partially paid, unpaid etc), and by the date that they were originally generated. You can then download a copy of any of your invoices as a PDF file, individually or bulk, or export the invoice data directly into Excel.