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 BrownMicrosoft Cloud Azure/Excel Solution DeveloperAsked:
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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).

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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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