When I started out in this business, I met a girl who said that her main income doesn't come from having sex wiht guys, but asking them for money and never returning it. She said when they visit she complains about a bill or something she has to buy for her son, and they usually volunteer to pay....
Another thing she said was that when she learns a guy has a lot of money, she phones him and tells him that she is in trouble and needs 3000 dollars. She tells them a story that if she won't get that money something terrible will happen. The guys usually give it to her thinking it is a loan, but when they ask for it she simply says she doesn't have it. The guys never cause trouble, she makes sure they are all married.
She told me back then that that she makes about 30.000 a year this way.
I am not saying this girl is doing the same, just be aware that women like this are out there. Best thing is to check out everything a girl says, even if it means a rude awakening.
I am still saying the honest way would be to pay her a monthly amount. Sugar daddy-sugar baby relationships are supposed to be like that. You pay her expenses so she can make herself available for you whenever you need her.