use-setup.js

const useSetup = (setup, plan) => {
    const ref = useRef(plan);
  
    useEffect(() => {
      ref.current = plan;
    }, [ plan ]);
    
    useEffect(() => {
      const data = {};
      const actions = {
          submit: () => {
              alert('paying with plan: ' + ref.current)
          }
      };

      setup(data, actions)
    }, []);
}

function App() {
    const [ plan, setPlan ] = useState('default plan');
    useSetup(setup, plan);
  
    return (
        <input
          value={plan}
          onChange={ event => setPlan(event.target.value) }
        />
    )
}