In general we try not to be very restrictive with demo contributions. However please follow these basic guidelines.
After you all you wrote the demo - give yourself some credit! You do not have to do anything elaborate but at a minimum please list your name and a way to contact you. Methods of contact can be an email address, or a web page with a contact form. Optionally you might also list your location, or other facts.
Credits can be listed in an included text or html file, or directly in the source units.
Documentation is not required. However if your demo requires any setup or special notes please include some sort of documentation as a text or HTML file. Comments in source code are also welcome.
Some basic license must be included and referenced as a text file, html file, or directly in the source. If you are unsure of a particular license to use, simply state "This demo is put into the public domain.". This gives users full rights to do as they want with your demo.
If you want to retain some degree of attribution - that is so others cannot steal your work consider the BSD License or the MPL license. These are the licenses that Indy uses. Please refrain from using GPL as it is a "viral" or "infectious" type license.