FLStudio Mobile from the multitask switcher, Android: Shut down and restart your device OR kill the FLStudio App and restart it.
Relaunch FLStudio Mobile and repeat steps 5 & 6.
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Android <--> Android. iOS <--> iOS transfers. Windows <--> Windows
Transferring Apps and in-app purchases between operating systems is not possible, more info:
I own an Android, iOS or Windows version ...