Answered my own question
https://www.navionics.com/usa/blog/post/one-app-for-all-your-devices/
One app, one subscription
This improvement allows you to use the same subscription on smartphones and tablets. When you subscribe to the app on your phone, you can then install the same app on a tablet with the same operating system and restore all your purchases done within your account. Even with an expired subscription, your charts are still available, and you can download the detailed maps within your coverage area to your tablet.
