You purchased a script from a small developer who has since disappeared. The encoded files run fine, but you need to modify the script (e.g., change an API key, update a payment gateway, fix a security vulnerability). Without the original source, you are stuck.
Even the most advanced tools often produce "broken" code that requires extensive manual fixing to become functional again. Why Developers Seek Decoding Solutions
However, a persistent and controversial search term follows this technology: