I am creating a java based application which will have some questions topic wise . I am planning to make it available to persons for some fee. I will distribute it via email attachments since I dont have a website to host.
I dont want people should be able to install the same copy on multiple machines .How can I achieve that (some licensing kind of thing)?
Also the questions will be in a file . How should I encrypt them so that they are not copied/decrypted easily ?