The PATH license can be set either in an environment variable called PATH_LICENSE_STRING or programatically with the Path_SetLicense() function. For example, if you are running csh or a variant on a Solaris or Linux system, setenv PATH_LICENSE_STRING "2830898829&Courtesy&&&USR&45321&5_1_2021&1000&PATH&GEN&31_12_2025&0_0_0&6000&0_0" will set the PATH_LICENSE_STRING environment variable to the evaluation license. If you are running bash or a variant on a Linux system, export PATH_LICENSE_STRING="2830898829&Courtesy&&&USR&45321&5_1_2021&1000&PATH&GEN&31_12_2025&0_0_0&6000&0_0" will set the PATH_LICENSE_STRING variable. On a windows (XP) machine, you need to click on the "Control Panel", then on "System", then on then "Advanced" tab. Within this tab, there is an "Environment Variables" button, that you should click. You can then click on the button "New" and enter Variable name: PATH_LICENSE_STRING Variable value: "2830898829&Courtesy&&&USR&45321&5_1_2021&1000&PATH&GEN&31_12_2025&0_0_0&6000&0_0" Alternatively, (for advanced users) in your interface code, you can set the license with the following function call License_SetString("2830898829&Courtesy&&&USR&45321&5_1_2021&1000&PATH&GEN&31_12_2025&0_0_0&6000&0_0"); which, if used, must be issued before a call to Path_Solve() or any other license management functions. The above evaluation will allow you to solve problems of any size until December 31, 2025. After that time, you will revert to a demonstration license which only solves problems with up to 300 variables and 2000 nonzeros. Please contact either Michael Ferris (ferris@cs.wisc.edu) or Todd Munson (tmunson@mcs.anl.gov) for information on obtaining an unrestricted license.