If you wish retrieve printable invoices for your OSForensics license, you are required to login to your PassMark Account. If you have not set up your PassMark Account please use the "Forgot password?" link with your purchase e-mail address to create your account.
Once you have logged on, navigate to 'Invoices' from the menu on the left. This should present your list of orders as in the image below. From here, click the order number you wish to retrieve the invoice for.
This screen provides you with order information including the order date, delivery method and total price.
If you click the 'View printable invoice' link in the top right, this will open your printable invoice.