So essentially you send the encrypted serial number in a file or maybe upon entering the serial number you can create file. By logging your application running time you would see that if the total hours in a day exceed 24 then user is fooling around.Įnsure that your app doesn’t run without the config file.

Let’s say every time user starts your app by first setting date to 5th of the month.

Now by config file you would know that app already ran on 1 and 3 so user has messed up dates on the computer. Now after 30 days reverses the date and sets it to 2nd of month. Say user ran app on 1 and 3 day of month.

If user reverses the computer date, you would know that app was already run on that day.

Note the duration of the time application was open.īy doing the logging of timestamp you can avoid these workarounds:.

Make a note of time/date every time user starts the application.

Now create a configuration file which stores data in the encypted format and contain the serial number.Īdditionally implement these things in the config file.

You can use encrpytion to store expiry date within the serial number.

Use a special series of trial-serial number which stores expiry date in it.

I would suggest to implement few of things which are less intrusive and may avoid a normal user to either uninstall or buy at one month period.

If your price is a good value and people want to use it, most people will pay for it. The free software costs you nothing and their good will (and maybe recommendation to others) is worth a lot.įinally, write software that people want to use and price it for its value. If someone is in love with your program so much that they're willing to break your trial limits, let them. Users with a network home directory (e.g. Whatever you do, don't use the MAC address or an other hardware ID. You might name the file something innocent if you want to obfuscate things just a bit. In this case, putting something in ~/Library/Application Support//. Go for the 80/20 solution: the easy solution that gets 80% effect for 20% effort.

And they're unlikely to pay for the software anyways. Determined hackers will break all but the most over-engineered solution. This issue comes up repeatedly on the cocoa-dev mailing list and the consensus answer is always do the simplest thing possible.

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