For recreation permit, there is no limit. For commercial watermen there are a fixed licenses per year pending on the health of the bay.
Permit is issued to individual adults. One bushel per permit per day. Kids need no license. If you are serious about crabbing and intend to feed the family, need to invest 50 to 75 dollars to get the gear up.
Do a search on the net to get the trot line ready? It was a lot fun when the kids were young, I recall. The crabs are the sweetest you can find because they are fresh.
I am old school. Integrity is to do the right thing even when no one is watching.