You can install eWallet on your Apple iOS device from the iTunes App Store
All software for iPhone, iPod touch, and iPad is distributed through the iTunes App Store. Visit the App Store in iTunes on your desktop, or the App Store app on your device, and search for "eWallet".
If you have already purchased the app once, you can download it again at no charge as long as you are logged in with the same iTunes Store account (Apple ID). Newer versions of the App Store app have a list of your purchased applications under Updates (iPhone, iPod touch) or as a toolbar item at the bottom of the App Store (iPad).
The eWallet app purchase will only give you eWallet for your Apple iOS device; the desktop version is a separate purchase.