Users should be able to access their monthly invoices by logging in to their Seller Labs Dashboard.
From the left side menu, select Settings > Billing. You can view each invoice under "Payment Activity". If you click "View Receipt", in the Action column, it will give you a full page version of the invoice and allow you to download a copy for your records.
If you login to your Seller Labs account and do not see a subscription or invoices, you should be able to find your invoices in Feedback Genius. To access your monthly invoices, login to Feedback Genius click your email address in the upper right corner tool bar menu and select Settings from the drop down menu. From the left side menu, select Your Subscription. You can then view each invoice, under "Recent Payments".
For information on changing your billing address, please visit: https://support.sellerlabs.com/seller-labs-account-general/how-can-i-change-the-address-used-for-my-invoices