We happen to think that the service is very well thought out and ensures the integrity of your notes. However, they are not strictly necessary if you have no need to backup or export your notes.
If you would like to use Insight Notes for a time and then later decide if you want the backup and encrypted exporting subscription, you are absolutely free to do so. The first time you sign up to backup your data, you will be prompted to input an email and password for our servers to recognize you, verify your purchase with the App Store, at which point Insight Notes will do a complete backup of all of the notes that are saved. Your first 30 days are free.
You are free to cancel your subscription at any time. If you cancel your backup and encrypted exporting subscription, you can still keep using Insight Notes as you were before (just without your backup and encrypted exporting capabilities) and the app will continue to function normally.