Answer:
How customers rate/value her services
Explanation:
Since Henriette did not set a basic/standard fee for her services, she is bound to have non-uniform pay by different customers. This non-uniform pay is as a result of how much value or worth her customers attach to her services, as it affects them.
If she decides to get a standard prices attached to her services, she would have to consider how satisfied customers have been in the past, with her services.
Cheers.