Upgrading via Play Store (Android) and PayPal (Web)
Refund is available within 14 days. Please provide your TickTick account and transaction ID to support@ticktick.com.
Via iTunes (iOS)
Sorry that we can’t provide refund directly according to iTunes limits, you may report your request to Apple Support:
https://reportaproblem.apple.com/
Note: Make sure you cancel the subscription from the platform where you purchased TickTick Premium to ensure you'll not be charged again.