Upgrading to Sequoia, for some reason, finally broke my old, pre-subscription use of Fantastical.

(It's not that I don't like the app… I'm just perfectly happy with the functionality of the old version and don't need any of the newer features.)

In completely unrelated news, I am not charging enough for my subscription.

@marcoarment I had the same problem. Delete and reinstall fixes it. After that, the About box will say “Fantastical 2 features unlocked”.