I created a program once that had to connect to the internet before it would even run. and the thing was it checked for this in more than one spot during the running of the program, also hard code it everytime dont just call it. ** to prevent easy hex cracking** So if you have a server thats always running or a site etc.. you can actually have it during the exe of the program do a few things .
1. can always do a check sum ** good for more than just security**
2. make it username/password only accesible via serial # on your program then do a check on exe's start. good for security
edited: 3rd. for added security you could associate a username/password/serial with a mac addy