Question

Where do programs save their secret license or install related information? I notice that often times when you uninstall a program, clear out appdata references, check registries to make sure there is no residue of any relevant information.

If you reinstall the trial program again, it seems to know it was installed before. I’m not looking to find a way to crack trial programs but actually need to implement something similar and can’t find any good information on how to do this.

Answer 1

• Registry
• online
• file in folder Windows with system like name
• I even seen apps that hacked unused OS variables to store custom data in registry.
• But the simplest method is to register a handler for a custom unused file type like .sof (if that is there, it was installed before) Edit 1 You have to register the handle to open a known executable on the system, not to your app. Because cleaners will detect if points to a no longer existing app location. As for storing additional params like date of trial expiry you can include them in the path as a param, like: cmd.exe -o 2010-02-09