From Fedora Project Wiki
Fedora Notes
This license is extremely permissive, and falls under the "Copyright only" category of licenses, where it is effectively in the Public Domain, but Copyright is still retained. The license contains an optional clause where, if the recipient feels that the licensed work is "worth it", they have the option to purchase the copyright holder a beer. If this were mandatory, it would make this license non-free, but since it is optional, it does not consist of a use restriction. As written, this license is Free and GPL compatible.
The original license was found here: http://people.freebsd.org/~phk/
License Text
/* * ---------------------------------------------------------------------------- * "THE BEER-WARE LICENSE" (Revision 42): * <phk@FreeBSD.ORG> wrote this file. As long as you retain this notice you * can do whatever you want with this stuff. If we meet some day, and you think * this stuff is worth it, you can buy me a beer in return Poul-Henning Kamp * ---------------------------------------------------------------------------- */