Can I keep my newLISP scripts closed although newLISP is licensed GPL?
Yes, you can. The gnu.org FAQ for the GPL explains this. As long as your scripts do not use other 3rd party GPL’ed software in the form of imported libraries or loaded modules, your newLISP scripts don’t need to be GPL licensed. Most modules on the newLISP website are unlicensed and don’t import other libraries. If they do, consult the licenses of those 3rd party libraries. newLISP allows you to distribute a binary of the interpreter together with closed source. When using newLISP in your software always mention the www.newlisp.org website in your documentation as a place where source code for newLISP is available.