If you have purchased the tracker on IOS, you can access your data across all your devices on IOS. To use it on those devices, simply click Restore on the purchase page of additional devices to gain access.

If you purchased the tracker on Android, your devices should automatically restore the tracker on additional devices as long as you are logged into the same Google account that made the original purchase.

Unfortunately, Google and Apple do not communicate together and share purchase history. So if you purchase on IOS, it does not translate over to Android and you would have to purchase twice (and vice versa).

If you use the same login credentials, your user tracking data will sync across all devices, both Android and IOS