Many online public libraries use DRM protected ePub ebooks. They are protected using Adobe Digital Editions DRM (digital rights management). The problem is that Android reading apps don't support DRM-protected ePub ebooks. Luckily you can remove DRM protection from public library ebooks. So you can free your ePub ebooks and read them on any device that you have including but not limited to Android phone or tablet,
Kindle,
Sony Reader,
Nook,
iPad...
You don't need to be a hacker to crack the encryption of DRM protected ePub files using ADE DRM. Just download freeware
ebook DRM removal tools archive including DRM removal tools for ePub files. And try to use
Calibre plug-ins first.
Note: Public libraries allow you to borrow ebooks for a limited period of time only. So delete your borrowed ebooks after this period is over. Please do NOT abuse DRM licenses.