There is an option in Bloodborne to write a note to remind yourself and others online of hidden treasure etc. Within the Notebook > Notes Made option, you can press 
to protect a note.
What does this option do? Is there a maximum number of notes you can make?
Best Answer
There is a limit of 10 notes that you can have active at any time. Once you reach the limit, older notes are overwritten (presumably in order of writing).
It's worth it to save good notes that provide you with a lot of Fair ratings, so they'll continue to provide healing bonuses.
See also: Reddit