How do trial versions of programs keep track of time?

Question

Programs that I have downloaded who's trial period has ended, even when reinstalling keep saying that my trial has ended. I wondered how corporations kept track of PCs which have used their trial.

Is the fact that the trial is over stored in the registry somewhere or in the tempfiles? Perhaps it is some kind of HWID lock which logs your MAC address?

Would love to know if anybody has any idea.

Answer 1

There is no standard method for this so it will depend on what code the software developer writes. For instance that code could just store a starting date based on your clock, or if more sophisticated it could actually get the official date from the internet. As to where it stores this, the registry is just one of the options available to programmers, it could also store it in the hidden application data folder, or something called isolated storage in .net, or on any other folder on your system. It could also send a unique ID and start date to their server and periodically check against that. The storage can be encrypted or unencrypted. People who crack programs reverse engineer the specific method that was used, but it would require in depth knowledge, unless it's a very unsophisticated method, like storing it in human readable form in registry.

Most programmers who really want to protect their software would certainly not choose this method.

Answer 2

It varies with different software but generally it's always data stored in the registry. The most common I've seen is an expiration date stored in the registry so regardless if you uninstall it, the installation leaves that one key left in the registry so when you install again, it reads that key as already being expired.

Edit: Going further on this, some software doesn't even base it on an actual date, just keeps track of time passed and then puts in a registry change after x time has passed.