Overtrace
Support
Email xiangmucheng001@gmail.com and I will reply. Including your device model and iOS version helps.
Restoring Pro on a new device
Open Settings in the app and tap Restore Purchases. Use the same Apple Account that holds the subscription or Lifetime purchase.
The camera view is black
Overtrace needs camera permission to show the live view. Open the iOS Settings app → Overtrace → enable Camera.
My reference keeps moving
Tap Lock at the top right. While locked, the reference will not move, scale, or rotate until you unlock it.
Where are my images stored
Only on your device. Nothing is uploaded. Deleting the app deletes them.