A locked watch, or one you're not wearing, never alerts — that's an Apple rule: the alert falls back to the iPhone. Wear the watch unlocked (wrist detection on) to receive alerts on your wrist.
This is also an Apple limitation: custom sounds are not allowed in watchOS notifications. Dropp's melodies play on the iPhone and inside the app.
Dropp Settings → Upgrade to Dropp Pro → "Restore purchase". The subscription is managed and cancelled in your App Store account settings.
Dropp collects nothing — everything stays on your devices. Details in the privacy policy. Deleting the app deletes everything.
A question, a problem, an idea: contact@dropp.care.