If your flash drive is big enough to store everything you purchased, then it is possible.
If you have the full programm with all real-tracks, I personaly know of no flash drive/memory stick that is bigg enough.
I personaly have my BandInABox installed on a external USB/Harrddrive. They are not that expensive an still have enough free space to install things to come in the future.

I also splitt konsequently the programm and my userdate. So therefore a never store my own stuff in a BandInABox or RealBand Folder.

I have not tried the new SSD-Drives that are much quicker than regular harddrives but all you can gain ist faster programmstart an faster load of other programm stuff.