Depending on your goal, follow the specific guide below to get the correct version for your 64-bit Windows 7 system. 1. Flex: The Fast Lexical Analyzer (for C/C++ Developers)
Use the Flex setup executable from SourceForge. download flex for windows 7 64 bit
The GnuWin32 project provides a stable port of Flex for Windows. Depending on your goal, follow the specific guide
If you are looking to build cross-platform desktop or web applications, you need the (formerly Adobe Flex). Apache Flex® - SDK Installer Depending on your goal