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FEATURE

Trial Versions

Make your time-limited trial difficult to break

Issue: 4.6 (July/August 2006)
Author: Christian Schmitz
Author Bio: Christian Schmitz is the creator of the Monkeybread Software REALbasic Plugins.
Article Description: No description available.
Article Length (in bytes): 8,697
Starting Page Number: 31
Article Number: 4611
Related Link(s): None

Excerpt of article text...

This article is about some ideas on how to make a time-limited trial of an application. There are a few limits we have to keep an eye on and a few strategies on how to limit the user from resetting it too easily.

Where to Save Data

The first thing to do is to think about where to save the preference data. The preference data includes all the user settings and the information about your time limit. In a limited user account or with the user account on a network server you have only two real places for saving your preferences: the Preferences or Application Support folder. All other folders are likely to be read-only to the user. And no, you do not want to ask the user for an Administration Password to save your preferences in some other place!

There is always the risk that the user deletes your preference file to reset the time period. However, the user will not like to delete the file if you have some more data stored there and the configuration of the software takes some time. For example, a mail client could store the mail accounts with the time limit counter data so a deletion of the preference file requires the user to set up all the email accounts again.

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