I have performed a little bit  at the professional level as a vocalist.
I usually have the music memorized.  But, many times I have seen vocalists
perform with the score in front of them.  It seems to widely accepted for
the soloist  to use music if it is an oratorio or a Bach cantata or any
other kind of work if it is not a staged work. But, for recital purposes,
I would think that the music should be memorized. After all, the word
recite means to speak or sing or play something from memory.

As far as instrumental music is concerned, I have seen it several ways.
Pianists usually have their music memorized.  Other instrumentalists use
their music ALL THE TIME, even when performing as a soloist.  I don't know
if that is just what is accepted among instrumentalists or what, but I do
not think it's too much to ask to have a solo work memorized.

Stephanie Scherrer <[log in to unmask]>