I have a script which seems to have quite a bit of demand. Currently it has a simple install. I get around 10 downloads a day on it. Right now the script is totally free, I haven't really decided if it will stay free or not. What I really need to know is the big differences between a simple script with a small install and a full fledged script people will pay for. I'm guessing I need to look at security, and creating a decent admin system. Anything else I need to pay attention to?
Perhaps i just need to add an admin system.. it has good features already and is very easy to integrate. Maybe I can add some different designs.
You can continue giving it out for free and create a support page for it, forum, templates, add-ons and charge for those services. A lot of scripts are free and then if you want to get an add-on for it you pay like $20. But it depends on what script you're dealing with.