The LUFA library is currently released under the MIT license, included below.
Everyone is free to use LUFA without payment - even in commercial applications where the product source code is not publicly disclosed. However, use of the library must be in accordance with the library license conditions.
If you wish to use LUFA without payment, you must include a copy of the full license text below with your product or project - on your website, and in an accompanying manual or other materials for the product. As long as the entire license text is made available and obvious to the users of your product, you are free to incorporate the LUFA library into your product without special additional licensing.
In some instances the small requirement for public disclosure of LUFA within a product is unwanted; in these instances a commercial license is offered up as an alternative to the standard LUFA license.
Commercial entities can opt out of the public disclosure clause in this license for a one-time US$1500 payment. This provides a non-exclusive modified MIT licensed which allows for the free use of the LUFA library, bootloaders and (where the sole copyright is attributed to Dean Camera) demos without public disclosure within an organization, in addition to three free hours of consultation with the library author, and priority support.
Please visit the Commercial License link on Library Resources for more information on ordering a commercial license for your company.
LUFA Library Copyright (C) Dean Camera, 2013. dean [at] fourwalledcubicle [dot] com www.lufa-lib.org Permission to use, copy, modify, and distribute this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies and that both that the copyright notice and this permission notice and warranty disclaimer appear in supporting documentation, and that the name of the author not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. The author disclaims all warranties with regard to this software, including all implied warranties of merchantability and fitness. In no event shall the author be liable for any special, indirect or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortious action, arising out of or in connection with the use or performance of this software.