How to prevent duplicate credentials being entered on 2 different user devices

If user A inputs credentials into a mobile app (first name, last name, Email ID and reference number) in order to unlock the app; whats the best way to prevent user B from inputting the same credentials as User A onto their mobile device in order to unlock the app? (Both user A and B having the same app installed on their devices).

I'm thinking IMEI and storing that information on a central database but is that possible in hybrid app and is there another way without IMEI?