Copy Protection for Java software

The project is to add a simple copy protection system to a web based java software that I will be selling. The software is written in java and runs under a tomcat webserver. It comes in a zip file for either windows or Linux. I would like some kind of authorization process to be added to the software. It needs to be all browser based so the first time a user browses to the software they go to an authorization screen. The authorization process doesn't need to be to complicated but I need suggestions on how it could work. It would probably be best if they needed to enter a unique text string that they received in an email. Somehow this text string will only work one time. It could also be that they enter their email address or order number and the software checks to see if it is authorized and/or already in use. I'd also like to be able to give a 15 day trail of the software. I'm not looking for something perfect. I know that with this type of software it is hard to protect. It just needs to be a bit complicated to get around so that it's easier for someone to buy the software rather than try to hack it. As part of this job I also need to have instructions on how to integrate the code into new versions of the software. This means I need to have the new code and instructions to integrate it into the software myself. I have attached a short video overview. If you are interested in this job I will also send you a copy of the software files. Thanks, Joel.