Google's Android operating system for mobile devices is the best operating system of its kind on the market. I know because I've used a ton of devices on a ton of different networks.
Android applications purchased from their 'market' application are registered to the Google account associated with the phone's owner: presumably you.
These applications, once purchased, can be ported to new devices, so you don't have to re-purchase the applications. Say, for example, you drop your cellular phone and need to buy a new phone. Do you want to re-purchase the applications you'd paid for once before, are familiar with and presumably like? No, you don't want to do that.
There is an issue, however, with applications porting over correctly on occasion. Occasionally, the applications won't show up in your 'downloads' menu.
To solve this problem, you can do a 'factory reset' and re-add the primary Google account associated with the user who purchased the applications. Check once again if your applications are listed under 'downloads' in the 'market' application where you purchase apps.
I was able to salvage a ton of applications I'd purchased without purchasing them again. However, it took two factory resets, which wasn't a problem seeing as it was a new phone. I didn't lose any information.
