Source: http://feeds.gawker.com/~r/gizmodo/full/~3/tdqxv-K6ULQ/the-life-of-an-iphone-app-nasty-brutish-and-short
Our breakdown of the 500 million apps populating the App Store was correcto: A study by Pinch Media shows only 20 percent of people use free apps again after the first day they download it.
After a month, the rate falls off to about less than 5 percent. Paid apps fare a little better, but not a whole lot, as you can see. It's pretty remarkable that the average app is so crappy or disposable you only use it for a single day, and within a month, you're almost definitely not using it. The presentation says that long-term users are "generally 1 percent" of total downloads. These stats—and a wealth of others in the presentation—are based on over 30 million downloads tracked by Pinch.
For developers, the big takeaway is that it doesn't pay to just give your app away—unless you're in the uppermost echelon of successful apps, there's no way you'll make any money with ads in a free app. There is, however, evidence that offering a free lite version of a paid app can boost sales.
But generally speaking, your app is going to have a short shelf-life: In the App Store, because of the way it's designed—for "maximum turnover—and because of the way people appear to be using their apps. It helps if your app is a game, which fares a little better than other cateogries, and you know, maybe if your app doesn't just make fart noises. [Pinch Media via TechCrunch]