A single license for USB Safely Remove is reasonably priced (often ). You get:

The phrasing “642 license key” is a pattern frequently associated with:

Ever get the "Device is in use" error? This tool tells you exactly which program is holding your drive hostage so you can close it safely. One-Click Ejection:

If you want, I can draft a specific support message using details you provide (purchase email, approximate date, transaction ID).