Mobile App to Open a Door (Flutter?)

I would need a simple app/widget to open a door when a button is pressed. The door opens when sending a get-request to a certain url. The app should be licensed for 1 day, 1 month or 1 year and the license should only be usable on one device (droidactivator might do the job). For one-year licenses, 30 days before it ends, there should be a reminder "license expires in XX days". Alternatively, we could just think of using a login for users but they can only have one account per device. So once an account is registered to a certain MAC ID, it cannot be used on other devices anymore. Everytime the button is used, it should be written in a google sheet: license number, user name, user apartment, timestamp. A widget with the same button is needed, too. This is the rough way how it should work. Some smaller details might have to be added. Ideally, the app should be based on Flutter and work on IOS and Android. The app should be submitted and the source code handed over