When the app version updates will it automatically upgrade to Mobile Passport plus?

No.

When the app is updated this does not automatically sign you up for the paid premium Mobile Passport plus service. You will only be charged if you choose to make the upgrade. After opening the updated version of the Mobile Passport App you will find screens introducing the Mobile Passport plus premium service. You may choose to upgrade or stay with the free version of the Mobile Passport App. Payments will only be charged to your device account upon confirmation of purchase.