So you installed Wakeout on a new device and found yourself locked out despite having an active subscription? No worries!
On the payment screen, scroll all the way down and you'll see this magical button:
Just tap on "Restore Purchase" and let Wakeout do its thing, automatically detecting your active subscription.
Just a heads-up: your new device must be on the same iCloud account where the original purchase was made.
Enjoy and have fun defeating the sedentary apocalypse!