Hi welovecats and welcome o the club! (My wife & I also are cat people. Our two little sisters turn one at the end of the month). I see you bought the "Batman" bass. Alembic serial numbers have moved around a little over the years, but will usually be found in one of the following places:
- on top of the peghead
- on the fretboard below the last fret
- on the truss rod cover
If you don't see one in any of the above, try looking inside the control cavity.
Enjoy your new bass,
Bill, the guitar one