Have you considered selling as a product (script/app) rather than service?
We're dealing with real money here because BTC is real currency so don't mind inquiries. Part of due diligence especially when not all of us are elite codemonkies/Business Analysts.
Well the thing is, it's PHP, so if you give the code to someone, he can then give it or even worse sell it again after, there is no serial thing. This is why I'm offering this as a hosted service rather than a product (meaning the code itself). I hope you understand that.
But the only part of the bot that uses the API-Keys is the Trigger part, you still can use all the other features without giving your API-Keys.
And if I was selling as a product, I could not provide the SMS alerts, which is I think a good feature.
I'm also planing on adding other features with SMS, that would for example allow you to send an SMS to query the bot so that it gives you back the different current market prices right on your phone, and also to directly place orders by sending an SMS to the bot.