title: How to protect PDF files from being downloaded or copied
body: <p>I'm developing a new website with PHP &amp; MySQL.</p>
  
  <p>The website is for an online eBook library that grant access to its books based on paid subscription plans.</p>
  
  <p>So, I need to make sure the PDF files of these books are well protected and can't be saved, downloaded, or in anyway copied.</p>
  
  <p>How can I do that?</p>