When you start the program after the trial period has ended or a subscription key has expired, the Register Subscription dialog appears:

If you don't have a subscription key, click the Purchase Subscription button to open Maxprograms Online Store in your default browser and purchase a key.

Type your subscription key in the Subscription Key text box and then click the Register Subscription button. On success, the Register Subscription dialog closes and you will be able to continue using Fluenta.