How to prevent an ASP NET MVC application requesting authorization from Google every hour?

Question

We are using packages Google.Apis.Calendar.v3 and Google.Apis.Auth.Mvc in an ASP .NET MVC application with users.

We want each user to have access to their Google Calendar, so it is necessary that each one of them give permission to our application. We have read a lot and it is said that there is a way to prevent the application from asking the user for these credentials every hour

We have looked at solutions like this and do not work for us

solutions like this one we do not know how to use them in our MVC application

users may or may not register on our site using google

This is the last code that we tried and everything works correctly, except that every hour the users who had already given permission to our application had to do it again and to re-authenticate with google and give permissions:

FlowMetadata implementation

    public class AppFlowMetadata : FlowMetadata
    {
        private static readonly IAuthorizationCodeFlow flow =
            new ForceOfflineGoogleAuthorizationCodeFlow(new GoogleAuthorizationCodeFlow.Initializer
            {
                ClientSecrets = new ClientSecrets
                {
                    ClientId = "MY_VALID_CLIENT_ID",
                    ClientSecret = "MY_VALID_CLIENT_SECRET"
                },
                Scopes = new[] { CalendarService.Scope.Calendar },
                DataStore = new FileDataStore("Google.Api.Auth.Store")

            });

        public override string GetUserId(Controller controller)
        {        
            var userId = controller.User.Identity.GetUserId();
            return userId;
        }

        public override IAuthorizationCodeFlow Flow
        {
            get { return flow; }
        }
    }

GoogleAuthorizationCodeFlow implementation forcing offline

    internal class ForceOfflineGoogleAuthorizationCodeFlow : GoogleAuthorizationCodeFlow
    {
        public ForceOfflineGoogleAuthorizationCodeFlow(GoogleAuthorizationCodeFlow.Initializer initializer) : base(initializer) { }

        public override AuthorizationCodeRequestUrl CreateAuthorizationCodeRequest(string redirectUri)
        {
            return new GoogleAuthorizationCodeRequestUrl(new Uri(AuthorizationServerUrl))
            {
                ClientId = ClientSecrets.ClientId,
                Scope = string.Join(" ", Scopes),
                RedirectUri = redirectUri,
                AccessType = "offline",
                ApprovalPrompt = "force"
            };
        }
    }

AuthCallbackController

    public class AuthCallbackController : Google.Apis.Auth.OAuth2.Mvc.Controllers.AuthCallbackController
    {
        protected override Google.Apis.Auth.OAuth2.Mvc.FlowMetadata FlowData
        {
            get { return new AppFlowMetadata(); }
        }
    }

Test controller action

    public async Task IndexAsync(CancellationToken cancellationToken)
    {
        var result = await new AuthorizationCodeMvcApp(this, new AppFlowMetadata()).
            AuthorizeAsync(cancellationToken);

        if (result.Credential != null)
        {
            var service = new CalendarService(new BaseClientService.Initializer()
            {
                HttpClientInitializer = result.Credential,
                ApplicationName = "TEST",
            });

            IList list = service.CalendarList.List().Execute().Items;
            var selected = list.First();
            EventsResource.ListRequest request = service.Events.List(selected.Id);
            request.TimeMin = new DateTime?(new DateTime(2017, 1, 1));
            request.ShowDeleted = false;
            request.SingleEvents = true;
            request.MaxResults = 10;
            request.OrderBy = EventsResource.ListRequest.OrderByEnum.StartTime;
            Events events = request.Execute();

            return View(events);
        }
        else
        {
            return new RedirectResult(result.RedirectUri);
        }
    }