Actually, it is worth to post it. That's the whole basis of open-source programming. The problem is that not many LFS users don't really understand the open source policy, and then they start to flame.
If a player leaves and connects after a while, he can have another UCID.
You should save the time when someone buys a ticket in a .txt file or in a database or whatever and check that time the next time that player buys a ticket.
Open up your C script with the C editor;
Search for the line you want to alter;
Edit it;
Press F5;
Check if it works;
Press Stop in the editor;
Save your work;
Build your script into an .exe file;
Done.