While searching for "free license keys" often leads to risky or fraudulent sites, the most reliable way to use AudioRanger without cost is through its built-in free tier. The AudioRanger License Story
That being said, here's some general information about Audioranger Pro and potential legitimate ways to access it:
How to Get an Audioranger Pro License Key Free
Batch-edit the tags of thousands of audio files at once. Select, Edit, Cut, Copy and Paste just as in a spreadsheet editor. Multi- AudioRanger Frequently Asked Questions - AudioRanger