If you own a legitimate older version of Adobe software, you can find your activation details through official channels:
Searching for "Adobe PDF Converter 5.53" suggests this is not an official Adobe software release. Authentic Adobe products use names like Adobe Acrobat Adobe Acrobat Reader Adobe Acrobat Standard/Pro Understanding Adobe Licensing Adobe Pdf Converter 5.53 License Key
Adobe has moved away from "license keys" for most modern products in favor of a subscription-based model via Adobe Creative Cloud Official Product Naming If you own a legitimate older version of