If you want to convert image (scanned) PDFs, you need to purchase a license for Able2Extract Professional PDF Converter. The difference between the Standard and Professional edition of Able2Extract is that the Professional edition has an OCR engine that can convert text from scanned or image-based PDF files, along with converting your native (electronic) PDFs.
In case you already have a license for Able2Extract Standard, there's no need to buy a full license for the Professional one. You can simply upgrade your current license at a discounted price by visiting our Upgrade Center here: http://www.investintech.com/prod_updates.htm
This article refers to Able2Extract Standard and Able2Extract Professional.