I have an older version I think PCStitch 6. Must I buy the whole newest version, or can I pay for an upgrade?
The latest version of the application is PCStitch 10. Unfortunately, you can't upgrade directly to the latest version, because only the latest version is available for purchasing. I have checked the official website, and the only thing you can buy is PCStitch 10 priced at $49.95.
Buy application: https://www.patternsonline.com/SW/PCStitch/Order.ASPX