Yes, your Herald Premium digital subscription will enable you to access Premium content within your current NZ Herald IOS or Android app and as well as on the website. Just ensure you are signed in.
To Sign In:
Open the app.
Tap the 'Profile' icon in the bottom navigation
When the Profile screen opens tap 'Sign In'
Fill out your email address and password
Tap the 'Sign In' button at the bottom of the page