Data management system licence advice please

[pelinor]

Hi there - just looking for some advice. I designed a complex data management system for a company (based on PHP/MySQL) a while ago and now they want their sister company to use the same system and have asked me to send the sister company instructions on setting it up. Now, I put a lot of work into custom designing the system and I feel like I'd just be giving it away for them to use again, which I'm not happy about. Admittedly they've paid for the work (though I undercharged them) but what are my options? Can I legitimately charge at least a "consultancy fee" or something? I didn't provide any kind of licence. Any advice gratefully received. Thanks, Mish.

[flann]

You can certainly charge them for you time to set it up and I would also charge a set up fee as well as an hourly fee.