If at 10, I didnt know this, you can store the script within the toolbox file than you would be able to password protect it. Thats very interesting. I feel however that you shoud add copyright clauses to your code as comments and allow users to take your code to use as their own. A very easy way to learn and create in python is through adaptation of other works. I know thats a bit open-sourcy for a forum surrounding a closed source program suite but In this aspect you should allow people to get at your code. Perhaps a Creative Commons set up if you arent planning to sell the script but still want to be acknowledged as its originator. If you look at some of the code pasted around here or on the resource center, we tend to mention with in code comments when parts have been borrowed from others.
