Thanks.. but u say yes and yes, then tell me about buying an external battery? So is there a way to get the app on my phone without paying $9.99 again? IF so, HOW?

I downloaded the app initially on my ipad. In case I run into a low battery at a tournament, I want a backup. How do I download it my android platform cellphone without paying another $9.99? Or cant that be done? Or what if I want to have someone else's ipad as a backup, do they also have to downloa...