Custom "E-Reader" Functionality for Private Content

I'm looking to have customers have view only access to blog posts (which they cannot copy/paste) which they buy for a set price or have access to through a subscription. The cool, custom functionality I'm looking for - ANYWHERE! - is the functionality an e-reader has but directly on a WordPress page, where the customer can underline and make comments on the content, so even though they cannot download the content or copy/paste it, they can have all the reading functionality directly on the page. If they are logged in, their notes/marks will be saved with the content. I want to have my cake and eat it too insofar as reserving my content only to my customers so I can sell it at a premium while also giving the customer all the functionality of a .doc download. Is there ANYTHING for this type of purchase of a blog post? I think it would also be perfect for the plug-in/theme you have for online courses and e-learning, so the students can do everything right in the page while also preventing them from dispersing content freely. Thank you for your help!