We speak plenty regarding customer lifetime sales in magento. It’s truly quite vital once making decisions around marketing / advertising pay and more specifically the return you get on a channel (i.e. — PPC).
Running this report in Magento may be a little bit of a pain, however as luck would have it an easy MySQL query will solve your problems. the subsequent MySQL query provides you a listing of customer emails, names, and total purchase amount over the life of the customer (since the dawn of time!).

SELECT DISTINCT customer_email, customer_firstname, customer_lastname,
SUM(subtotal_invoiced) AS Total
FROM `sales_flat_order` AS a
GROUP BY customer_email
ORDER BY SUM(subtotal_invoiced) DESC