Sign into your account and in the navigation go to: My Account > Billing and Password. Click on the "Invoices" tab and you will see all of your invoices that you can view/print. Under Billing History is a list of all of your invoices with the amount and the date they were paid.
Multi-User Plans have consolidated billing, which is paid/processed by the Administrator. Individual users in that plan will not see an invoice. Only administrators can view their multi-plan invoices.