Software evaluation - licence

Question

Hi,

Can any one help me on software licence module. We created a new application and want to release a demo version(30 days trial) of our tool later we need full version. How can i generate license file or license code and how to limit 30 days evaluation. Please give me some help on this.

Our application is developed on windows in QT

Answer 1

Although I don't see the connection to patents it's as easy as that:

• Save the installation time
• at any startup check whether 30 days are reached
• provide a mechanism to unlock the software eith a license key

Answer 2

There could be several possibilities:

• Timestamp and encrypt the date of installation somewhere safe(registry or an external encrypted file)
• Upon each run, validate the registry date as well as the system date.
• User may tamper with system date/time; so you may would want to validate the system date/time wrt previous run date/time, and plan you app's actions accordingly.
• Show the app-dormant error message upon currentDate - installationDate > 30, and provide a link to your online registration page.

You may also require to:

• Develop a keygen(key encryptor) that would generate(a hash out of a certain key) the serial key.
• Add the key decrytor in your product that, upon getting the key from user input, would try to generate the same(hash?) key and compare that hash with your decryptor algo.

Checkout this and this that uses SerialNumberTemplate to get serial number during installation.

--EDIT--

You can note the time either from:

• The date of installation: Create a Custom Action in your visual studio setup project; and add registry item in Install override method.
• The date from first-run: Use DateTime.Now.Date to get the current date and encrypt/save it somewhere, probably registry.