Pika is free software distributed under the terms of the zlib/libpng license. The license is not a copyleft license, meaning derived works do not have to release the source code. You can use it in open source, commercial, personal and educational projects.
Pika Copyright (c) 2008, Russell J. Kyle This software is provided 'as-is', without any express or implied warranty. In no event will the authors be held liable for any damages arising from the use of this software. Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions: 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required. 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software. 3. This notice may not be removed or altered from any source distribution.
As you can see the license is simple and straight forward. It means you cannot claim authorship of the code and if you distribute or change the source code the original copyright must remain in place. If you distribute a binary that contains Pika then credit does not need to be given but it would be nice.
The following are other software projects that have been incorporated into Pika. They each have licenses of their own that are compatible with Pika’s license.
The pseudorandom number generator used in Pika is based on the Mersenne Twister and distributed under the BSD license. For more information on it visit http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html.
PCRE – Perl Compatible Regular Expressions
The RegExp module uses the PCRE library and is distributed under the BSD license. For more information visit http://www.pcre.org/.