from iphone to new samsung tablet

That is correct. There are three different apps for Traveller, one each for the three operating systems that Traveller is capable of operating on. If you are using more than one of these three operating systems then you must purchase the appropriate app for each of the operating systems you are using. Go to the top of the page and click on "Products" then on "Traveller." When you are on the "Traveller" page the "Costs & Options" tab will explain it to you. You will still be able to use your iOS device if you wish to or further along the track purchase a new iOS device and use your current app on it as well as still being able to use your Android device.

Agree with what has been said.
An explanation if I may to clear up some confusion.
When you change mobile platforms..ie move from Apple device to Andriod device (in your case Samsung) ..then you have to buy another Traveller package to work on that particular specific platform.
Why?
Because each mobile platform..has their own seperate OS (Operating System), its' that stuff behind the scene so to speak, that make the laptop, smartphone do stuff when you tap on the screen.
They use different code to work..so applications have to be specifically written for each different mobile Operating System, so there is a specific Traveller App for Android OS, Windows OS and Apple OS.