Enterprise Developer Build Tools for Windows requires the same license as the Enterprise Developer IDE products (i.e. Enterprise Developer for Visual Studio or Enterprise Developer for Eclipse) so you need to ensure that you have enough licenses to cover your use of both Enterprise Developer Build Tools for Windows and any other Enterprise Developer development product on Windows.
For example, if you have purchased six development licenses and install one instance of Enterprise Developer Build Tools for Windows you can install an IDE-based Enterprise Developer product or Enterprise Developer Build Tools for Windows on a maximum of five other machines.