Piano question?

Question

When a note that is normally sharp or flat in a piece is labeled as neutral, does it stay that way until the note has a sharp or flat by it again? Or is it just neutral for that measure?

Answer 1

It is just neutral for that measure.

Answer 2

Usually it is only for the measure, in the next measure the key signature applies. You can make your notation clearer to the performer by adding courtesy accidentals.