If I download the Android app now, and a new version of the app with an in-app upgrade feature is added in the future, will I miss out on that feature? Or will my app be updated to the latest version, so I can upgrade as well?

I'm new to Android apps so I don't know if it's possible to receive updates to apps.
Cheers! Thought so, I was just making sure.

Now to find a way to pay for apps without having to get a credit card.