Units Converter is the tool available in iPhone App Store. It is not free anymore and it needs US$0.99. If you have installed it while it is free and then press the App Store icon on iPhone today, you probably notice there is an update. But, the App Store does not shows you clearly whether it will charge you $0.99 for the update.

I have downloaded the update through App Store on iPhone directly. My iTunes account does not shows whether it have charged me or not. Since the app is now the top paid app, I think probably it charged me already.

Since there is a lot of free web apps to change units, I will download the app for free but not for the money. It’s a pity that App Store does not tell me clearly it needs to pay for the update. (I hope I am wrong for this) What if all other freeware apps suddenly becomes paid apps, then charge me a thousand dollars?

Be warned. Do not update the software on iPhone’s App Store directly. Update it on iTunes.