Commercializing a php application?

Question

Say I have developed a php webapp and would like to distribute it for others to use as proprietary software. Is there anything I can do short of some sort of licence or just trusting the customer to avoid having to provide a hosted solution? Clearly if I just distribute the application to paying customers to host independently, I run the risk of them leaking the code.

Update:

Some of the responses so far suggest obfuscation. However, this won't prevent another user from simply plopping the leaked obfuscated code onto their servers and reusing it. Granted they won't be able to modify it..but I am looking for something more complete. Any ideas?

Answer 1

Obfuscating it can go a long way. Many users won't try to figure out the logic.

You can also add a registration key -- something that calls the mothership and acts like a dongle.

Edit: What I was going for with the registration: You can sell licenses by the domain, and require users to register their domain at your website after they buy.

One script I bought requires activation at their website. (The script is obfuscated as well.) Don't enter the domain, the software ceases working after a certain period of time. Transfer domains, and the software ceases to work.

I don't know the mechanics but the basic idea is that you want to guarantee that the script is running at the domain the purchaser said it was running at.