Yes, you can cancel anytime. Check the app for the links. For details, check the seller terms.
The subscription is sold either by Apple or Google depending on your platform. You can pay with all methods that the seller accepts in your country.
You need to get the sensors separately. Check the supported sensors and links to buy them from supported environmental sensors.
We are happy to help you. In case you have questions, please write to us.
Download the app and get started for free.