unity admob video reward

hello, implement admob a unity in the 3 types banner, interstitial and video reward that works well for me on the mobile, but my question is how I would make the video of the reward that is coin checking if the user finished watching the video or if I close it.

This is the code I am using.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using GoogleMobileAds.Api;

public class LogicaAds : MonoBehaviour
{  
    private BannerView bannerAdd;
    private InterstitialAd interstitialAd;
    private RewardBasedVideoAd rewardAdd;
    [SerializeField]
    private string  appID="";
    [SerializeField]
    private string bannerID="";
    [SerializeField]
    private string interstitialID="";
    [SerializeField]
    private string rewarID="";
    
     void Start()
    {
        PedirInterstitial();
        PedirReward();
    }
    private void Awake()
    {
        MobileAds.Initialize(appID);
    }
    private void PedirBanner()
    {
        bannerAdd = new BannerView(bannerID, AdSize.Banner, AdPosition.Bottom);
        AdRequest pedir = new AdRequest.Builder().Build();
        bannerAdd.LoadAd(pedir);
    }
    private void PedirInterstitial()
    {
        interstitialAd = new InterstitialAd(interstitialID);
        AdRequest pedir = new AdRequest.Builder().Build();
        interstitialAd.LoadAd(pedir);
    }
    private void PedirReward()
    {
        rewardAdd = RewardBasedVideoAd.Instance;
        AdRequest pedir = new AdRequest.Builder().Build();
        rewardAdd.LoadAd(pedir,rewarID);
    }
    public void CLickShowBanner()
    {
        PedirBanner();
    }
    public void ClickShowIntersticial()
    {
        interstitialAd.Show();
        interstitialAd.Destroy();
        PedirInterstitial();
    }
    public void ClicShowReward()
    {
        rewardAdd.Show();
        PedirReward();
    }
}

You can find the whole process here

Admob Into uniity