Why is the Premium Mode a subscription?
Many users expect the app to be adequately maintained, always available for new devices and iOS versions, and to gain new functionality. However, that means a lot of work has to be put into the app and work costs time and money.
Many apps, including Hyperion, have been funded solely by attracting new users who are purchasing premium content. If the growth of an app goes down and with it the number of new potentially paying customers, then there is no money to continue updating the app for the people who already bought it. Therefore, I decided to offer the optional Premium Mode as a subscription. With approx. 5 EUR/USD a year you contribute a small amount (unlike many other app subscriptions) and so every subscriber helps to promote the further development of Hyperion.
However, if you do not like the subscription, you can still use the app without it. If you previously bought the In App Purchase Comfty Mode, those features will stay.