You can access associated invoices for a specific customer on their subscription page on Stora.
To do this search for the customer using the search function in 'Contacts'.
Select the relevant customer name.
On the customer page there will be a section titled 'Invoices' where you can view all invoices associated with that customer.
To see each invoice in more detail simply click on the invoice number.
For customers who have more than one subscription, you can view invoices associated with each subscription by clicking on the Subscription ID.