To have access to your company's Billing & Subscription page you have to be either a Master or Billing user.
From the KaseyaOne Home page you will see the Billing & Subscriptions page on the side-bar. In order to view the invoices you will need to switch from the default "Active Subscriptions" tab to "Invoices" tab in order to view all your company's invoices. You will also be able to filter and search the list of invoices by the Status, Due Date, Invoice Date, etc.
Check out the Billing & Subscriptions page article to learn more.