Is there a free trial for Robo App?

Yes, the app offers a 3-day free trial period. You will not be charged during the 3-day free trial period. The billing will start after a 3-day trial ends from the day you installed the app.
 
If you find the app is not useful as per your use case, you can uninstall the app within the 3-day free trial and you will not be charged.