You may use the operating system to move and create copies of the files on your computers for your personal use as needed, as outlined in the license agreement. Indeed, I highly recommend downloading to your hard drive of your main system, and distributing it to your other devices from there, as necessary.
All I ask is that you follow the spirit of Copyright law: copies you make for your own purposes and convenience are okay, but you cannot distribute copies to others, put copies on Torrent networks, or sell copies to others.
The PDF files are also printable, so if you want to create a printed copy for your own personal use, please feel free to do so.
