On a label attached to the bottom or back of the DJ controller. License Card:

That said, here are a few general suggestions on how to obtain Virtual DJ or its LE version legally:

It sounds like you're looking for a specific serial number or "exclusive" key for VirtualDJ LE 7.0.3, but it’s important to be cautious: sites claiming to offer "exclusive" serial numbers for software are often deceptive and can lead to malware or phishing.

There are several ways to obtain a Virtual DJ LE 7.0.3 serial number. Here are a few options:

Version 7.0.3 is quite old. Most modern controllers come with "Virtual DJ Limited" or "Serato DJ Lite," which are automatically detected via USB without needing a manual serial number entry.