An ideal example is how our own Copy Protection Works. When our application being demoed was expired, it generates an activation key based on the system time converted into an ascii code. This activation key will then be passed to us by the client for authorization key generation. The authorization key will be generated based on the formula supplied by the programmer (ofcourse fully documented) then to be passed back to the client. At the client side, the authorization key will be keyed in to activate the expired application either into FULL VERSION or EXTENSION OF THE DEMO.

>Hello,
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>I want to know ideas about how to require an activation key after installing my EXE application. A different key, of course, for every computer.
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>Is there any method using random strings?
>I have seen some case where the program generates a first string and the user types the second part (provided by the programmer, of course), but i don't know how it works.
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>Thanks
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>Juan Carlos