[Piper_]

Switching (via registering and de-registering) between different accounts works on Kindle for PC just like it does on a Kindle device, except you can only open and read the books K4PC is currently registered to. If you want to open one downloaded from an account you aren't currently registered into, just go to the options page, de-register and register to the account from which it was purchased, and it will open.

The only quirk is that your K4PC "Home" page will show all the books together, without separating them by account.

As with the Kindle device, the archive page will only show the books on the account you're currently registered into.