If you are an original owner of X4 and have lost your key, you don't need to look for "verified" numbers on third-party sites. You can retrieve it legally through these steps:
If you're interested in purchasing Chief Architect Premier X4 or verifying your existing serial number, you can: chief architect premier x4 serial number verified
If your project file becomes corrupted in a pirated version of X4, the official support team will not be able to assist you. How to Retrieve a Lost X4 Serial Number If you are an original owner of X4
Chief Architect uses a sign-in based licensing system for modern versions (X15+), making old-style serial number verification obsolete for official products [7]. Your Product Key (required for activation) will be
Your Product Key (required for activation) will be listed alongside your software downloads.
: Your verified serial number and associated product keys are managed through the Chief Architect Online Account in a section called the Digital Locker Hardware Lock Option