Using cloud storage is optional... and does not preclude you from keeping your "original" versions on your own hard drive
I don't use cloud storage, so if you do not have your books on your own hard drive, I suggest you talk to an Adobe staff person to find out how to copy your books back down to your own hard drive
Adobe contact information - http://helpx.adobe.com/contact.html may help
-Select your product and what you need help with
-Click on the blue box "Still need help? Contact us"
Or ask in the InDesign forum
The Cloud forum is not about using individual programs
The Cloud forum is about the Cloud as a delivery & install process
If you will start at the Forums Index https://forums.adobe.com/welcome
You will be able to select a forum for the specific Adobe product(s) you use
Click the "down arrow" symbol on the right (where it says All communities) to open the drop down list and scroll
BUT... do be aware that InDesign files may not be backwards compatible... if you opened/saved the files in the Cloud version, you MAY not be able to open the files in the CS6 version
You can download your books, documents and images from Adobe server before you terminate the subscription. Have you tried logging in to your account? Try it and see if your stuff is still there.
Paying $50 every month for something you don't use is simply silly in my opinion. I would resort to the old version or CS6 version that was the last perpetual product from Adobe.
Creative Cloud is a subscription and you have to continue paying the subscription for as long as you want to continue using the product. This means for life.
For some reasons I don't see what has been posted before me so the duplication occurs here. I try to avoid this but can't help it. I missed John's post and it is nearly one and half hours he posted. Something is definitely going wrong on these forums today.
I'm not sure I follow exactly what you mean. If the books you wrote were InDesign files you created in a past versions of the product they would be typically be files saved to your computer. How did they get to the cloud? It sounds like you signed up for a Creative Cloud membership. If you signed up for Creative Cloud you would have to continue for however long you agreed to when you signed up - typically either a monthly or yearly option, if its $30 a month that sounds like a yearly option at a promo rate. If you don't want to continue your membership you should cancel when it comes time to renew. See Cancel an annual membership (individual or team) here: Cancel your membership or subscription | Creative Cloud
I'm not sure exactly what you mean about your books, so its hard for me to make recommendations. Creative Cloud memberships do come with online or cloud based storage which can be accessed using a browser at https://assets.adobe.com/files but files only get put there by you uploading them. If you cancel your membership your storage will automatically downgrade to free level of 2GB storage.
This might have some useful info for you
Creative Cloud Help | Creative Cloud / Common Questions
Hope that helps,