After registration, you will have your amazon kindle account from which you can log in and access the store through kindle device. (usremotesupport.com)
But there's no way to have 2 kindle accounts in use on one device except on PC. (goodereader.com)
... register my new iphone to my amazon kindle account First, download the Kindle app on your phone Set it up with your user information once it is downloaded If it doesn't automatically offer to sync... (fixya.com)