Updates to the latest version of FoldingText should happen automatically, and going to FoldingText > Check for Updates... should check that for you. Currently the latest version is not a dev version, but the released 2.1.1 version. Can you tell me if you've bought the App Store version or the Paddle version of FoldingText?
Regarding FoldingText, and TaskPaper, please consider them completely separate apps. If there's a specific question about their relationship, please let us know and we'll try to clarify as much as possible.