raylib is licensed under an unmodified zlib/libpng license, which is an OSI-certified, BSD-like license that allows static linking with closed source software:
Copyright (c) 2013-2016 Ramon Santamaria (@raysan5)
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:
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.
Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
This notice may not be removed or altered from any source distribution.
The following fonts provided with raylib are free to use (freeware) and have been designed by the following people:
scarfy spritesheet and fudesumi image have been created by Eiden Marsal and licensed as Creative Commons Attribution-NonCommercial 3.0
medieval city 3d models and textures have been created by Alberto Cano and licensed as Creative Commons Attribution-NonCommercial 4.0