How to implement 30 days expiration?

[Devman]

Hi guys,

I am at the stage where I am putting shareware crippling into my project, and I would like your help in how to implement a 30 day expiration feature. Basically, when 30 days have passed since installation, I want to disable features.

I have a binary settings file that I plan on writing the install date into, then examining that each run to see if 30 days have passed, but what if someone just uninstalls my software and reinstalls it, wiping out that file in the process? How can my installer know that my program was previously installed if there is nothing left after the first install?

How do you implement this such that you can enforce a 30 day time limit? I am not concerned about hackers who can crack my "security": I don't expect to defeat that crowd, but just for the majority of normal users to have it secure against them being able to unlimitedly use my software after the 30 days.

Thanks!
Devman

[Wayward]

Here are some related threads from the archives:

• Setting time limits for a demo game (Dexterity 07-2004) asks how best to implement time limits for a demo. Replies suggest using the registry. You could also keep track of the date of last use to combat users changing their system date to extend the trial period.
• What's the best way to implement a time-limited demo? (Dexterity 12-2003) asks how to implement time limiting without using the registry. Suggestions are to create a file in a system folder, or use an off-the-shelf solution like Silicon Realms' Armadillo Software Protection System (now known as Software Passport).
• Where to hide timeout values in demo versions? (alt.comp.shareware.authors 09-2004) has concerns that security/user privileges in XP may prohibit changing the registry or writing to a system folder. Suggestions include: don't worry about users uninstalling and reinstalling, or use the timestamp of the uninst000.dat file. One post provides a mored detailed explanation on how to use the registry.

[Dom]

Use a registry key to hold the data. Check it at the start of your program, , and if it doesn't exist write in todays date. if it does, just read it & use it.
Most casual users will balk at the thought of editing the registry so its fine for them. Power users will think nothing of hacking the registry, but then they think nothing of getting cracks & serials, so your not losing real sales.

[Devman]

Thanks for the help, guys!

I'm not crazy about leaving registry keys on the system after the users uninstall my program, but oh well, it's not that big a deal I guess.

Peace!
Devman

[James C. Smith]

To implement our time limits we leave behind a tinny little registry vale even when you uninstall the game. We have hundreds of thousand of users playing our demos and there have been about 10 or 20 people who have written to customer support complaining about this. Some users demand to know what we did to their computer and accuse us of causing all their computer problems. Of course, having one value added to an unused part of their registry can’t possible cause any problems. But it makes them nervous to know something was left behind. You will have to be prepared to help these people nicely or just ignore them.