If you are selling advertising then your customers are your advertisers, not the audience that you supply them. Users may be customers in larval form, but it is

If you are selling advertising then your customers are your advertisers, not the audience that you supply them. Users may be customers in larval form, but it is a significant step for a subscription model business to convert a user to a customer. Many startups fail to pay attention to this soon enough (e.g. before they go broke).