Since you have already purchased Data Bridge and Design Extender, you don't need to purchase another upgrade. you only need to log into your webassist account and go to the Download center page to download the current version.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.