Legitimate Adobe software receives updates to close security loopholes. Portable versions are frozen in time, leaving your computer vulnerable to exploits. How to Legally Access Adobe Fireworks CS6
If you are looking for a portable-like experience—fast, lightweight, and built for the web—it is highly recommended to move to modern tools that have surpassed Fireworks in functionality:
A browser-based (and desktop) tool that handles vectors and prototyping even better than Fireworks did.