From your profile page:
- Open the app. Tap your account's profile picture in the top right corner.
- Under INKR Extra Subscription, tap Get INKR Extra.
- Tap the "$4.99/month" button, then follow the instructions of the App Store/Play Store.
From a subscription-locked chapter:
- Open a subscription-locked chapter from the chapter list.
- In the Viewer, swipe to the end of the chapter preview.
- Tap the "$4.99/month" button, then follow the instructions of the App Store/Play Store.