If you choose this route:
: You are performing a security audit on software you own a valid license to use, assuming the End User License Agreement (EULA) permits reverse engineering for security verification. When Decoding Violates the Law
Ioncube is commercial software. Using an unauthorized decoder violates the Ioncube license agreement and, in some jurisdictions, anti-circumvention laws under the DMCA or EU Copyright Directive.
: The source code inside encoded files is still protected intellectual property.
Do not run such executables on any machine with sensitive data.