If you are responsible for your organization's billing, you can access all related information from profile page in the billing section.
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On the left side, you can see the current plan and your usage. On the right side you see some information on how you pay and what will be on the invoice.

In order to view a list of payments and invoices, follow the link in the section Payments. You can also use this button to go there directly:
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You will see a list of all your payments. Just select an item to see all the information on that payment. From that screen you can also select Print to generate a PDF (or actually print).