LyX wiki has a page dealing with a portable setup (https://wiki.lyx.org/Windows/PortableInstallation) -- not to be confused with how to make portable TeX documents (http://wiki.lyx.org/Windows/LyXWinTips#toc5). Another rather detailed portable setup guide, only in Spanish this time, is also available at [url]http://self_loving.blogspot.com/2013/10/lyx-portable-lleva-lyx-contigo-en-un-usb_20.html[/url].
A ready-made portable LyX package exists at SourceForge.net but is manifestly obsolete by being v2.0 and not updated since 2012: check https://sourceforge.net/projects/portable-lyx-20/; although deprecated, it might still be a good source for a working portable launcher.
About the same time a PortableApps.com discussion about making LyX portable took place and I'm inclined to believe it was the inception of the SF.net package (see http://portableapps.com/node/27981).
Moreover, a separated Lyx offer for Windows exists that purports to install a complete environment and contains plenty of related documentation, but it is outdated as well: https://sourceforge.net/projects/lyxwininstaller/.
http://www.lyx.org/Home wrote:LyX is a document processor that encourages an approach to writing based on the structure of your documents (WYSIWYM) and not simply their appearance (WYSIWYG). LyX combines the power and flexibility of TeX/LaTeX with the ease of use of a graphical interface. This results in world-class support for creation of mathematical content (via a fully integrated equation editor) and structured documents like academic articles, theses, and books. In addition, staples of scientific authoring such as reference list and index creation come standard.
Latest LyX release is currently v2.20 (announcement at http://wiki.lyx.org/LyX/NewInLyX22) and installers can be downloaded from http://www.lyx.org/Download.