professional mistress
An upscale prostitue who services a small number of men (usually executives) on a regular, long-term basis in exchange for them contributing to her financial well being. Each man may call on her anytime on his regular day (eg. 1st & 3rd Tuesdays). If he needs her for a Friday,Saturday or other days, additional negotiations are necessary.
I could never be a protitute - having to hustle for johns and taking risks, but being a professional mistress is great because I am in control of who I see and when, and the guys I pick really take good care of me.