My C program called Mathematica several times during the execution. However, after 4 or 5 times Mathematica stopped and then I got this message.
/home/sec/.Mathematica/Licensing/mathpass:3: The Mathematica license you are using has expired. Please contact Wolfram Research or an authorized Mathematica distributor to extend your license and obtain a new password. Error detected by MathLink: MathLink connection was lost..
Is this the licence problem or technical problem? I am using Mathematica 9 Student right now.