Hi, Jennifer!
This is a great question, and an issue I just dealt with on my own
Annual Pass. If you renew your current Annual Pass within the 30 days and get the discount, the expiration date remains the same regardless of the next time it gets used. In your case, if you activate in on September 5, 2017, it will expire on September 4, 2018, if you renew before October 4, 2018.
If you do not renew with 30 of its expiration, you lose the discounted price. Personally, it was beneficial for me to forfeit the discount, and let mine expire and buy new when I returned. Since it would be 4 months until my next visit, it made sense for me to pay the higher "new" price than to have it unused for that amount of time.
To remain eligible to get the Annual Pass discounts on future booking and to be able to make my FastPass+ selections, once my last Annual Pass expired after the 30 day window, I purchased a new one online. It is linked to my
My Disney Experience allowing me access to room discounts, as well as FastPass+ booking. On my next trip, I will activate it at a ticket window, therefore starting my new "year".
I know this can be confusing, so if you need clarification, please
reach out to me! I will be happy to help a fellow Annual Pass buddy!
Cathy