If you are launching a service on the Internet, there is always the temptation to offer a free plan to entice the public.
You think people will like it - and want to upgrade to a normal plan with full features. This is a big mistake. If a person is completely satisfied with the free tariff, then he will stay on it forever !
And it will demand from you reliable service, new functions and make claims. The less the user pays, the more noise he makes on social networks and the more support he requires. Negative reviews come from free users, not from paid ones (this is quite logical if you think about it).