There is a flow-on effect in the way consumers interact with a service provider, too: per account, you'll receive more complaints from free users than paying ones; vice-versa, more constructive suggestions from paying users than non-paying users. This result is explained as a choice-supportive response [look it up; "the tendency to retroactively ascribe more positive attributes to a choice invested into"], since the opposite behaviour would be a source of cognitive dissonance. It can be a source of frustration to paying users that their suggestions/requests are not then more highly valued by the service provider.
This is SOOOOOO true! It's because monetary value comes with commitment!