Hello,
I can add some protection to your EA like:
-Expiration
-Limit usage to a specific account
-Limit usage to a specific name (user name or broker name)
-Limit usage to optimization, test or demo account
It is also possible to merge all of this conditions and add some other.
Notice that with the newer mql4 code compiler, they have improved the encryption and the decryption is quite impossible...actually if you ask to decompile a mql4 EA version +840 here in freelancer, few members will bid and they will ask thousands of dollars!