Licence manager page ASP.NET Web Forms

Question

We have an fairly complex enterprise ASP.NET web forms 2.0 app.

We need to deploy this application to our clients who are in closed VPN environment.

Application will be deployed to the instances of our clients(basically one instance is equal to 200 or more client PC's).

We need to create licence manager page where we can configure duration of one licence for all clients within one instance. If the licence expires there will be popup warning for clients that they cannot use the app anymore.

What is the best way to achieve this?

Answer 1

You want to have only one license per server, no matter how many clients and users are there. If the application license on server expires it will be not be accessible from any client by any user (except the admin console / license manager).

In such a case you can have a database entity (or XML or any other file as suites your requirements) that stores license information in encrypted form such as License Start Date, Expiry Date, No of Users, License Type, Issued By, Issued To etc.

Depending upon your application type and requirement, these credentials can be checked:

1. Upon every request (might affect performance) or
2. Upon every login by the clients (this seems to be a better approach) or

On license verification, if the license has expired then you may redirect the user to the license page.

Your license manager should be accessible only via a separate login

This scenario can be implemented only if do not deploy your code on the server ie you provide only compiled assembly to the client.

Update

Multiple validations can be applied for license tampering such as:

1. If the license code field is empty, user must be redirected to the registration page.
2. If the encrypted license code has been modified then redirect to registration page.