For the god-only-knows-how-many-th-time, if the code can be run it can be decrypted. If you've encrypted the code, you can't run it without shipping the key with it. If the key is shipped, it's just the same as shipping decrypted source. The best effort you can make is to make the script really hard to read.

Perlmonks friars and upwards - please stop front paging these nodes - they have no signal, just noise.