Basically you define the CheckSerial function in Code section of the script. Then you need to check if the entered serial is correct - you need to find your own secure algorihtm for that - Giving you one would be pointless for security:-) This way you can generate multiple keys that will fit the algorithm and pass your check.
And depending on that check you set Result to True or False - Inno Setup wizard will accept or reject entered serial depending on that. There are many if you want to get a general hang of the coding system.
Inno Setup Documentation
Also Inno Setup has online. Xyem: Out of curiosity, what are you attempting to prevent with this? If the continuation of the installation is based on the true/false value of a function, it would be trivial to bypass (redefine the function to always return true, extract the files another way etc.). SANTA!:-D Lol, Basically nothing really, I just had the idea that since atm I am backing up a large quantity of my games and to make it easier I was putting them in an install and putting all the installers either on discs or on a portable HDD. I know I am weird, by I just thought it would be cool to have a activation code, a WORKING activation code I mean, for each of the archives.
Inno Setup Compiler
I have the lastest Inno Script Studio 5.5.9. I added a custom message, but it does not show up when I run the. Inno will call the Check function whenever it thinks, to the best of its knowledge, that the entry in question should be used. The Check function acts as a sort of tiebreak, in effect. If Inno has already decided that the entry shouldn't be installed, then there's no point in calling the Check function - nothing it can do would change Inno's mind.
If I was doing it commercially I would definately consider investing in a pro one, but since I am not I just thought someone on here might have done it before.