App pricing confirmation

I was looking for a one off accounting solution built on laravel i can customise for as an accounting solution. I was looking to purchase the double entry and projects package.

Now I wanted to confirm if I install the packages, I will have to pay for the package after one year? otherwise it wont work?

You have to pay only if you want support and updates. Otherwise, you can use the app for lifetime.

But will the app(s) continue to work with newer versions of Akaunting?
(Hosted and/or self-hosted.)
Or might they break when the main app changes?

I noticed Double Entry had version number 2.1.7. Does it mean it's specifically for Akaunting 2.1.7, or does each app follow it's own versioning?