Its an app for the iphone called "Lose it!". And its free! I think there's a website too, that you can upload the information I put in the phone to the website, but I never used it. I know the app is free, but I never visited the website. As far as I know, there's no "program" to pay or sign up for. I just use it as a tool on my phone because its always with me and I can enter information from anywhere.
It has been my right arm in my weight loss journey this past year. It adjusts the daily calorie goal as your weight goes down. Whenever you enter a new weight, it will make a slight adjustment to your calorie goal. For example, when I started at 157 pounds, it gave me a daily calorie goal of 1900 or so and now, at 125 pounds, my daily calorie goal is 1600. Once you reach your goal weight, it re-adjusts your calorie goal to "maintenance level" , once I get to 122 pounds, it says my calorie daily level should be 1800 to maintain that weight. It takes your age and height into account when you set it up for the first time. Then you can enter how fast you want to lose weight. I have mine set at 1/2 pound per week, but you can set it for more. That setting also plays a part in the calorie suggestion is gives you.
My favorite part is that it allows you to view a whole week at a time so you can see if your over or above your calorie goal for the week as a whole. This is great for me because I allow myself one "cheat" day a week, so if I go over one day, I can "make up" for it on other days of the week or by adding extra exercise. In addition, you can enter your daily exercise and it will calculate those calories and take that amount of calories off what you've eaten for the day or the week, so you can eat that much more wihtout going over (good for my cheat day).
Overall, its been the best tool for me. Of course, its only as good as the information you put into it.