pay up

informal
to give someone the money that you owe them, especially when you do not want to:
Eventually they paid up, but only after receiving several reminders.
(Cambridge Advanced Learner's Dictionary & Thesaurus からの pay up の定義 © Cambridge University Press)

アメリカ英語辞典
to give all the money that is owed or asked for:
Some ballplayers charge fans $10 for autographs, and the fans, incredibly enough, pay up.
(Cambridge Academic Content Dictionary からの pay up の定義 © Cambridge University Press)

ビジネス英語
informal
to give someone the money that you owe them, especially when you do not want to:
After being taken to court, they finally paid up.
(Cambridge ビジネス英語辞典 からの pay up の定義 © Cambridge University Press)

- Cambridge Dictionary