encryption tool

Hi we've recently spent a lot of time and money assembling a group of autolisp codes, toolbars and a custom menu package to aid in the creation of structural steel detail drawings. We would like to make this software available to others in our field, at a price, of course. I was wondering if anyone is aware of an encryption tool and maybe a tool for creating time limited password prompted exe files that we could use for distributing our software on a time limited basis for others to try.