I think my title explains my problem quite clearly.
When I change my workspace I copy my .settings folder to the new .metadata folder:
.metadata/.plugins/org.eclipse.core.runtime/
This is so that I can transfer my font and syntax colouring preferences (preferences export doesn't seem to work).
When I relaunch the workspace Flash Builder launches as Standard on the splash screen and Premium features are disabled.
The problem is obviously related to my .settings folder thought I'm not sure exactly what I need to change to fix this.
Any suggestions gratefully received!