Wiktionary
pay up
vb. (context intransitive and transitive English) To pay in total a sum which is owed, especially when the sum has been owed for a period of time.
WordNet
Usage examples of "pay up".
Why not, then, now that the time had come, pay up gallantly, and remember of the episode only what had made it seem so supremely worth the cost?
Suppose we sell off all the horses, and sell one of your farms, and pay up square?
It'll relieve you, I'm sure, to know that instead of forty Earth standard days, you have an unlimited length of time to pay up.
On the other hand, if the Admiralty signs off on the idea of a station out here, they may decide to go ahead and pay up anyway.
But while people will pay up for an Emperor, especially if he has an army to collect for him, they’.