1) You should apply and get Viber Public account. https://www.viber.com/public-accounts/
2) Open your Viber mobile app, then go to Public Tab.
3) Tap on Public account you manage, tab on header, to go to account settings, and tap Edit Info
4) Scroll all way down to see Your app key - copy it.
5) If you can't see the app key - find "Your Chat Solution" - Check that Chat API is selected - and copy KEY to use шт Viberer bot.