Copy Protect Jar files

Hi Everyone,
How do I copy protect Jar files. I need this for licensing the software that we created. Is there any mechanism for this or any open source tools to do that
Thanks in Advance

Is that possible to protect JAR files from copying. Any Reply or suggestions on this is really appreciated.

This product might be something for you:
http://www.agilis-sw.com/ezlm/index.htm

/Svend Rost

The file itself can't be copy-protected. The code inside can certainly have a licensing mechanism (password-based or something else), although with enough time, criminal energy and and a decompiler, users will be able to crack this.

It's also worth reading this.

Thanks Guys,
Firstly, I would like to apologise for posting the same question twice. Reason I felt is that the first post was not clearly communicating. I thought I would make it much more clearer to get the appropriate answer.

I am looking for an opensource License management Tool or Copy Protection tool for packaging my software.

Few other questions follows

How licensing is done normally ?
I have couple of answers which may be wrong too

1) Requesting for a licensed file during registration which has the Usage period, number of license allowed for the customer and so on. License file may obtain from Registering through internet.
2) Providing a Key with the software Packaged CD

I want to restrict the usage based on the number of licenses provided and protecting from illegal copies. Any Ideas please !