Also at the bottom of the main page is the clear indication that it is a 15-day free trial, not a free trial, period. They ship you a 30-day supply, so 15 days after your order they charge you $87.13 (the price for a 30-day supply), and they will continue sending you product and charging you every month. This information is all clearly listed and easy to read in the terms and conditions.
The bottom line is that you should always read terms and conditions for anything/anybody who is getting your credit card info. And when something is "Free" you need to be even more wary as to what is the "catch" - because there frequently is a catch.