When should your kids start paying for hanging out with their friends

My High Schooler said she and her friends are going to starbucks after their mid-terms.  I said OK.  She said she needs money.

I said, "Uuuhhhh, I don't have money."  She ran upstairs and got her money.

I finally said, "You know, it's time you start paying for your time with your friends."

She gave a sigh and said, "I know."

She walked out the door and I felt a little bad.  When do you make your kids use their money for activities?