Ionic geofence in once at location

Every time I open the app, my app receives notifications each time, if i am on the location. How do I trigger the event only once in the location?
my code:

import { Geofence } from '@ionic-native/geofence';

@Injectable()

export class GeofenceProvider {

  constructor(public geofence: Geofence, public events: Events, public platform: Platform) {

    platform.ready().then(() => {
      if (this.platform.is('cordova')) {

        geofence.initialize().then(
          () => {
            console.log('Geofence Plugin Ready');
            this.addGeofences();
          },
          (err) => console.log(err)
        )

      }
    });

  }

  addGeofences() {
    // options describing geofence
    let fences = [
      {
        id: 'beerstore',
        latitude: 45.349094,
        longitude: -80.031466,
        radius: 20,
        transitionType: 1,
        notification: {
          id: 1,
          title: 'Beer Store',
          text: 'You are near the Beer Store.',
          openAppOnClick: true
        }
      },
      {
        id: 'wellingtons',
        latitude: 45.349094,
        longitude: -80.031466,
        radius: 20,
        transitionType: 1,
        notification: {
          id: 2,
          title: 'Wellingtons',
          text: 'You are near Wellingtons.',
          openAppOnClick: true
        }
      }
    ]

    this.geofence.addOrUpdate(fences).then(
      () => console.log('Geofences added'),
      (err) => console.log('Geofences failed to add')
    );

    this.geofence.onTransitionReceived().subscribe((data) => {
      console.log(data);
      this.events.publish('transition:recieved');
    });

  }

}

you could use Ionic Storage and save the Locations id.

Then before the notification, check if the new Location’s id is identical to the saved id.

Do you get notifications only when you Open the App?

when I in the location, It is enough to notify me only once. no need of notification each time of opening the app.