How to prevent clients from unobfuscating code from Ioncube?

I am going to encrypt that with ioncube when giving to a client side and I will simply include to call the licensing system. But the problem is when I simply include the code

include "li开发者_如何学Pythonc.php"

the user can directly remove the line to get the script worked. How can I write a script inside the lic.php which will make the script to prevent from running if the code i.e. is removed from the file? Note that I will include the line in all the php files in my script.

If you distribute the encoded script, the users don't see the source code and cannot modify it. That's the idea of an encoded script.