Let's analyse each image.
1 - You can't use the links in your browser, because you must provide a token.You can use a REST client, for example POSTMAN.
2 - On your mLab instance you should see two collections: (i) Clients and (ii) Temperatures. Check the temperatures collection. You should have multiple documents (database entries).
3 - The subscriptions are not correct. On the config.js file you should have: 'HOST': 'https://proiectiot.herokuapp.com'. After changing the file, execute this commands: $ git add . | $ git commit -m "Changed config.js" | $ git push heroku master.
You can delete your current subscriptions, in the subscriptions area (image).