Z3 is a theorem prover from Microsoft Research.
Z3 is licensed under MSR-LA (Microsoft Research License Agreement). 
See http://z3.codeplex.com/license for more information about this license.
Z3 can be built using Visual Studio Command Prompt and make/g++.

1) Building Z3 on Windows using Visual Studio Command Prompt

   a) If you a source distribution that comes with pre-generated 'build' directory,
      then go to step c)
   b) Execute
           python scripts/mk_make.py
   c) Execute
           cd build
           nmake

2) Building Z3 using make/g++ and Python
Execute:

   autconf
   ./configure
   python scripts/mk_make.py
   cd build
   make
   sudo make install

It will install z3 executable at /usr/local/bin, libraries at /usr/local/lib, and include files at /usr/local/include.
Use the following commands to install in a different prefix (e.g., /usr).

  autoconf
  ./configure --prefix=/usr
  python scripts/mk_make.py
  cd build
  make
  sudo make install

To uninstall Z3, use

  sudo make uninstall