I bought the latest version of infinite flight and installed it on my phone which is android 7.0
but because the latest version is not installing on my tablet which is android 4.4.2 so I was supposed to install the 16 version of infinite flight on my tablet, when I log in with my tablet it is giving an error that there is no subscription but on my phone, there is 1-month subscription.
even I log out on my phone and tried on my tablet but giving the same error.
From what I am aware, you need Live / Live+ to be able to play on the pre-global version of IF. Infinite Flight Pro subscription is only valid towards version 17+
To add to what @Ark_of_Ahmed.IF has said, the older live/live+ was abolished on October 11th(the day global was released).
If you bought a live+ before October 11th you should still be able to access live. Just ensure that you are still using the same google+ or Facebook account to when you purchased your sub.