You can subscribe to Moongate Premium in the Moongate app.
Open the Moongate app and tap the Menu button in the top right corner.
You will see an offer for Moongate Premium, tap "Subscribe to Moongate Premium".
On the next screen, authenticate with Face ID, and double tap the Side button.
You are now subscribed to Moongate Premium. You will receive immediate access to all benefits in the app. Thank you for your subscription.