Is it possible to install the Litchi app on my backup mobile device as well as my main phone. I always carry a pay as you go backup just in case my main one dies.?
From the Litchi Help FAQ:
You can install the app on as many devices as you want as long as they use the same platform and the same “main” account (Google, Apple or Amazon) that was used for the original purchase. If you wish to use Litchi on two or more platforms you will need to purchase it on each one.
Yes, I believe so. As long you have the same operating systems.