To pay up is to give someone the money that you owe them.
Examples of use:
1. You owe me £20. Come on, pay up!
2. Mr Brown was a good customer, he always paid up on time.
3. News headline: Judge tells woman – ‘pay up or go back to jail‘.
4. I’ve had a huge bill for my car repairs. I have to pay up before the end of the month.
||pay up and pays up|
Image © Dudley Carr