How should I protect my VBA code?

I write complicated macros for my engineering company. They do the job and I’d like to protect them properly.

As I understand, the VBA password protection is full of holes and there are loads of password recovery software out there that can hack through it.

What are the ways in which I can protect my code from hacking?

I also have found this software:
http://www.dombajsoft.com/protectvba.htm

I don’t know if its any good because there don’t seem to be any reviews available. Should I purchase a license?

I would be very grateful for any help. I would be really distressed if my code were to somehow escape this office and enter into a competitor’s hands!

Thanks in advance!