If you purchased an Independent Premium subscription directly via the website, you log in to the app using your email and password.
If you purchased your subscription via the Apple App Store or Google Play Store, you will need to register your in-app bought subscription before being able to log in with an email and password.
You can find out how to register your in-app bought subscription here - How to register my Independent subscription.
Open the Independent app
Tap the Login button
Enter your email address
Enter the password you created when you registered your account.
Then Tap "Log in"
Note: It is vitally important that the correct email address and password are used. If the password is not accepted, please try resetting your password here www.independent.co.uk/forgotten-password.