If you sync with your system calendar, any reminders added there will pop up a reminder from Diarium I believe.
So, i use the paid version on my Android phone mainly (i'm another ADHDer / autist with complex family needs), but on pc too. It's used for personal events and to help me manage / remember when:
- appointments, birthdays, events etc are
- when certain annual payments like council rates need to be made (stuff i don't have direct debits for)
- when different growth stages of garden trees & plants took place, so I can track effect of local weather & climate change on flowering / harvest times etc
- what tasks i need to do in home & garden
I use google calendar which has event, reminder & task integrations built in. I had anything I need a reminder for here, and it integrates with Diarium which adds the info in AND gives me reminders based on what I told google calendar to do.
Note: it doesn't double up - the integration seems to swap to just Diarium for reminders.