I had an Airline in the Airline Mode and now it says to me that I have to pay subscription, I really have to pay subscription to use my all-aircraft airline??
IFPAX changed to Subscription Mode, not a one-time anymore.
I might be wrong about this.
Yes, @Gabe_Z is correct, the link he added on his comment will give you more information.
Why was it changed to subscription mode?
Changing to subscription based model should also allow us to expand development and get a lot more features out that would add to realism. It should mean we can also have a dedicated support person. Monthly subscription will provide access to ALL sounds and features such as Emergencies, Airline Mode and Cargo Mode.