This version introduces a portable version of October for Windows users who may want to sync highlights from their Kobo on a managed machine where they can't otherwise install software.
You might also like to install it on a USB so you can use October across multiple computers without having to set it up each time.
Come to think of it, I suppose you could technically copy this version to your Kobo itself (which is basically a glorified USB) and carry it around that way. That said, I haven't tested this out so your mileage may vary! I think it would work fine though.
Upon startup, it will create a folder next to the exe containing settings files so just make sure to keep the exe and folder together.
While I haven't tested it extensively, one existing user seemed to have no problems using it.
Full Changelog: v1.5.0...v1.5.1