Yes it will be legal in another state, just like your car license tags are legal in another state.
Be aware of the Zebra mussel inspections. DO NOT leave your hull plug/bung in and make sure the boat is dry and outboard was put in the down position to drain its water if on a trailer.
Read up on the mussel inspection rules online, hours the inspection stations are open, etc for the lake your visiting. Lakes already contaminated may have post lake use inspections to prevent moving mussels.
It may or may not be a big deal depending where your going.