As long as it continues to work then it will work on your device. Unfortunately Apple many years ago discontinued the feature allowing transfer of mobile apps from computers. They now have to be downloaded directly from Apple whenever you get new equipment or erase equipment. If it is no longer offered by the developer then you either have to talk the developer into continuing the product, or learn to live without.
Click on this link to learn how to contact an app developer - How to contact an app developer - Apple Support