My Father always said, “you only get what you pay for” so he instinctively related price to value.

Now, the web has changed everything, and increasingly, “Free” is being used as a means to attract a target to trial, to deliver a generic service that leads into the other stuff, for which you can charge. However, much of the free stuff has a value, millions of Gmail users will vouch for that, and hosting this blogg, written on WordPress is free, but to customise it beyond a basic level costs. 

Generic is getting very hard to charge for as the marginal cost of providing the service is approaching  zero, so someone is going to offer it free in the expectation that 10% of those who sign up will move up to the paid model, where the product can be made specific to you, and so you become price insensitive, and the provider makes a dollar.

The more narrow and specific to an individual a product is, the greater the ability to charge.