One option I did, was to copy the whole external USB drive to an internal drive for regular use, and then tuck the external drive away as my backup. We can have an 3 active copies and a backup according to license agreement. But we can only run one license at a time.
PG has confirmed this is OK with a purchased copy.

Then I ran the installer and installed things so the programs can run on C: and the rest of the USB disk (Realtracks and Realdrums) is on the aforementioned internal E: drive.
This way my 120 gig USB is stored away and I can use the 500 gig E: drive to run Biab/RB and store everything (as if it were the external drive), including songs if desired.
I can run BiaB/RB from E: or C:, which is nice. My internal E: drive acts like the USB BiaB drive but is bigger and faster.
Or I run BiaB/RB from C: and use the Realtracks from E:

This reserves 2 of my 3 allowed install licenses but it sure is handy, especially when doing testing. I can have the latest/greatest test install on C: and know I still have the last stable release version on E: (or vice versa)
Plus I know I always have the original hard drive if needed, with very little wear/tear on it.
If I do have to take the USB drive to another (3rd) computer I have had little issue with running the program(s) from there since I still have the 3rd license available.

If your setup allows this, I've found it to be a nice way to handle things.

I do not work here, but the benefits are still awesome
Make your sound your own!