If you already have an active (trial) subscription/credit to the Nautical Maps app, we automatically add your new credit at the end of your current credit. That means you can renew or extend your subscription/credit at any time without having to worry about losing any existing credit.
You can see your current subscription/credit at the top of your profile screen, by tapping the icon at the top right of the app next to the search bar.
Your (trial) subscription/credit ends automatically.