Ok, my script is done. I want to sell it. It is encrypted by Zend. I want to sell my script online and wants to limit the license per domain. What would be the best way to create license codes that are tied up to a domain name? What I have in mind: 1. Some kind of algorithm based on the domain name. But I am no professional in coming up with some algorithm for the license code, probably whatever I think of, will be so easy for keygen makers to crack. But if anyone can give some tips to make it harder to crack, I'd really appreciate it. or... 2. Generate a unique license code and save it along with the domain in some database. Bad thing about this is the script has to always connect to my server somewhere just to verify if the script is running on the right domain. This script will be cheap, less than $20 maybe. Not a big budget software and I may not have the server resources if many people install it already and keeps on pinging my servers just to see if they are running on the right domain. What do you guys think is the best way to do this?