What would be the code for serial number authentication?

I am programming in visual basic 2008 I would like to set up serial numebers for software im developing. I would like to prevent software theft by ensuring that each purchased copy has a unique serial number that can only be used once. How would i create this so a.) The serial numeber can only be used once b.) The software cannot run without a correct serial number c.) The serial number verification box pops up on ONLY the first us开发者_StackOverflowe of the program and goes away after correct serial number is entered d.) a serial number generation and verification program

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Your question is very vague and dosen't have just a single answer. There are many, many, ways to accomplish what it is you are asking. The previous answers are attempting to push you to search Stack Overflow for other questions which may provide you assistance as to other ways the problem has been solved.

Have a quick look at the 'copy-protection' tag - there are many answers there that can help you on your way.

https://stackoverflow.com/questions/tagged/copy-protection

Regards Luke