Should you need to remove DRM from a rented library book for a bit past your due date, the following should help.

1. Download the current version of DeDRM from Alf (6.5.5, 6.6.1, 6.6.3, or newer — see UPDATE 3, below).
2. Unzip the downloaded DeDRM tools file
3. Open the application at the following location DeDRM_tools_6.5.5->DeDRM_Macintosh_Application->DeDRM.
4. Click “Select Ebook…”
5. Now open a browser and rent a book from your public library.
6. When it is available, download the book – I typically go for the ePub, which is viewable in iBooks or Adobe Digital Editions 2.0 or newer on a Mac.
7. A file with a .acsm might be downloaded from the library, double-click this file to open it in Adobe Digital Editions 2.0 or newer.
8. Inside ADE, an ePub of your book will be downloaded from the library and it will expire in a set number of days. Right click the book inside ADE’s library and select “Show File in Finder”.
9. When this book is shown in the Finder, drag it to DeDRM’s file select window (Step 4) titled “Please select a DRMed ebook” and then click “Choose”.

Success. A copy of your rented book will be stripped of its DRM and saved in the same directory as Step 4.

** UPDATE #1 ** 6.5.5 and 6.6.1 are not launching on macOS 10.13.6. Will look further into this.

** UPDATE #2 ** I never looked further into the above situation, but 6.6.3 is working fine for me on macOS 10.13.6.

** UPDATE #3 ** Catalina breaks compatibility. Calibre is the workaround. Haven’t tried this myself, but download Calibre and then run DeDRM as a plugin.