Your notebook is not persistent
At the current stage, your personal notebook is not persistent. You need to export your personal notes before you leave the meeting room (How do I export my personal notes?).
If you forgot about exporting your personal notes, the notes will be available until the meeting room closes, which is approximately five minutes after the last person has left the meeting.
There is a new notebook available in every meeting room
Personal notes currently do not follow you to other meeting rooms. You will have a fresh notebook available in every meeting room. You therefore need to export your notes before you change your meeting room.