If it was really encrypted it would be fine to keep it but as it isn't I can live without it.

Installing it at a customer site won't prevent them from reading the code using encryption. Competitors are more likely to get your code than customers even though it's encrypted. They have the skills to do it. What's the interest for the customer to "steal" your code?

To handle support when the customer has changed the code, which I'm sure you can figure out the first time they call, support just goes away and you start charging by the hour.

You buy a system because you don't want to do it yourself and not because you can't. I'd assume that it at least applies to the readers here...