Also, while I do like the expression "if you're not a customer, you're a product", it does not change the actual definition of the word customer.

> a person or organization that buys goods or services from a store or business

You may be confusing the word "customer" with the word "user"?

> 1. General: A party that receives or consumes products (goods or services) and has the ability to choose between different products and suppliers. See also buyer.

https://en.wikipedia.org/wiki/Customer

> In sales, commerce and economics, a customer (sometimes known as a client, buyer, or purchaser) is the recipient of a good, service, product or an idea - obtained from a seller, vendor, or supplier via a financial transaction or exchange for money or some other valuable consideration

I think to me the customer is the one receiving the product, whether or not they have actually spent money.

Also for consideration, "paying customer" and "non-paying customer" are common(?) phrases.