Hi,
I'm sorry but you would need to purchase a license via the Apple App store if you use Touchdown on an IOS device. There is no way to transfer the license.
You will also want to make sure that Activesync is available for your account on the server as we only connect with Activesync in IOS. Also, note that Push does not work the same way that it does in Android. It is a background sync that is scheduled by the OS.