Welcome to the Internet. Everything’s Free!
OK, so almost nothing is free. When we made a “Hire Us for Free” offer at Answer Guy Central, there were strings attached. They were minor, but they were strings nonetheless. When Angry Birds became free, a lot of people got to watch a LOT of advertisements. That’s not really “free”, either.
Now, a fitness-tracking App called Runkeeper is free. But you’ll find that only the most basic features are actually free. Runkeeper is making a big deal about how it’s their “Pro” model that’s become free, implying that it’s the good version of their service (there was always just plain “Runkeeper”, for free). But hey . . . you need Runkeeper Elite if you want the good stuff.