好多软件的，但这段话告诉咱们acsm文件的本质是网络在线图书……

A. When you borrow a ebook from public Library, what you are really downloading is an .acsm file. There is a lot of confusion about this file type as the .acsm is not your actual eBook. It is just a link to your eBook that allows a program like Digital Editions to download the actual book, When Digital Editions sees the .acsm file it will automatically download the PDF or ePUB file, which is the actual eBook,
If you do have Adobe Digital Editions installed and authorized correctly, then you won’t even see the .acsm file at all. It will do its job in the background of your ebook download. The purpose of this file is to communicate with Adobe’s content server and register the ebook to the Adobe ID that you have used to authorize ADE. If you don’t know how to do the authorization process, so you only remove drm from epub/pdf file, not from .acsm file, This is how to remove drm from epub/pdf file.

PDF ePub DRM Removal is tools to remove DRM protection and remove expired limitation of public library epub/PDF books. you can download windows version at here. , download Mac version

1). Install Adobe Digital editions, you can skip to next step if you have already installed.

2). Open .acsm file in digital editions, When Digital Editions sees the .acsm file it will automatically download the PDF or ePUB file, which is the actual eBook, and then unlock the file’s DRM so that it becomes readable.  At this point you should be able to read the library book in Digital Editions.

3). Run PDF ePub DRM Removal, it is easy to use, just select public library epub file from digital editions library folder, and click “Remove DRM” button.

4) When you’re ready to removal DRM protection , click “Removal DRM” button. After a few seconds, you’ll have an ePub/PDF book in output folder.

5) You can converter new epub pdf ebook to other format using Calibre after remove drm protection, look at this page

用PDF-XChange tool 4.0

具体什么软件，推荐一下呗

Adobe Digital editions

Adobe Digital editions