What is DONE page? What purpose?

DONE page is the history of what & when you did.

E.g. Phone app has “Recent call history”, right? It’s the same thing. Your events & to-do are added to this history when you tick items on ACTIVE page.

What is Edit & Clone?

Edit: You can edit Done history. Add your more detailed note/diary for the future reference.

Clone: You can set a new Reminder with same title & note.