Got invited to my cousins Spa party but don't want to go?

Im not mean i just dont want to go because it's going to be full of my cousin's 7th grade friends and plus it's a pool party supposedly and it just finished storming....anyways the invitation has a service card where I just pick what type of treatment I want and turn in the card in the party to get whatever service I chose.
My question is ... are these service cards pre-paid?
Will I had wasted my cousin's mom's money?
Or is it paid after the service?
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You don't have to stay all day. They were probably pre-paid. Keep in mind that you are lucky to have family. Don't dis them.
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However, I am going to edit that. There were times when I didn't want to attend certain events. And I didn't. Be your own person.