It sounds like you'd be fine with a developer key. Feel free to pop in and request an API key from your account settings API page.

Unable to fetch data when uploaded to google play store and downloaded through that. Do i really need a commercial api key?

@tridev said:
Unable to fetch data when uploaded to google play store and downloaded through that.
Do i really need a commercial api key?

No, you don't need commercial API Key.
If I understood correctly:

1. You've coded an Android APP.
   
2. You have uploaded the APP to the store, GooglePlay
   
3. You installed the APP on your device by downloading the APP from the GooglePLay store.
   

When you tested, were you using the same ISP that you used in the test on your computer? (Internet Service Provider)
In some countries like Russia, India, China, there are problems accessing the TMDb API Server.
https://api.themoviedb.org
What country are you in?
In some cases you get access with one ISP but you can't get access with another ISP.

And finally, there may have been some small code error in your APP.