So I am using free Mendix pro the new api that i added is not working so i was wondering is there a limitaion of how many rest call/API call i can use per application ?
There is no such limitation on using REST APIs. You can use as many APIs as you want.
If there's a problem with your REST call.
Pls send the Screenshot of the REST call so that i can know, where you are facing the issue.
Hope it helps!