This article explains why clients don't see the option to book a single session of a course (without buying the whole course), even though you've set a price per session. For clients booking the rest of a course that has already started, see How Is the Total Price Calculated for a Course That Has Already Started?.
When can clients book a single session of a course?
Clients can book a single session only when all of these conditions are met:
The course has a Price per session pricing option (or Price per session (in credits) or Price per session (in entries)). You add it in Edit course, in the Price section, with Add another pricing option. If you removed this option, clients can't book single sessions.
The time set in Open course spots has come (see below). By default, clients can book single sessions from 1 day before the course's first session.
The session still has a free spot.
The session isn't cancelled and hasn't started yet.
Don't let clients book this class isn't ticked in the course's Advanced booking settings.
Where do I set when single sessions can be booked?
Go to Settings › Bookings and rules, open the Bookings tab and find the Open course spots section. It applies to all your courses:
How long before the first session? — how many days before the course's first session clients can start booking single sessions (at least 1 day).
After the first session — tick it if clients should be able to book single sessions only after the course has started.
Then click Save.

