How to change my primary email and keep my ADE licensed eBooks?

I am moving ISP and so lose access to the old email address that I use to login to Adobe.com. How to ensure that I can still read the ADE secured ebooks that I bought and transferred to my Kobo e-reader previously. 

I am afraid of changing my primary email address on my Adobe ID account. Some older posts suggest that eBooks are licensed to an email address rather than to an account. And so I would lose some access. 

What is the best cause of action:

adobe id

email at eBook store

email on e-reader