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VB.net Security preventing user using it after trial


I am implementing the licensing functionality by Eric Moreau at the following link

I have the form that generates the license key working in my VB.net project which opens from

button click, but am not sure how to prevent a user that has gone over the 30 day trial from

using my application. What code would I use in the Application start up?
Murray Brown
Murray Brown
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2 Solutions
Éric MoreauSenior .Net ConsultantCommented:
in the test key button, the code check for the validity and display a message if it is not.

in your case, you should display a message to the user and open a disabled application letting him request a valid key or just close the application (if the previous message is clear enough to know what to do).
When your app starts for the first time, just encrypt smth like "Anonymous_" + DateTime.Now.ToString("dd/MM/yyyy") and write to registry. Every start check this value and compare date part with DateTime.Now. After registration replace this value with encrypted user name/key pair.
Murray BrownMicrosoft Cloud Azure/Excel Solution DeveloperAuthor Commented:
Thanks very much
Murray BrownMicrosoft Cloud Azure/Excel Solution DeveloperAuthor Commented:
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