Does an application on Android from Play Store require an additional?
Any application you install from Play Store can be correlated with a new software you install in your computer. Yes, all the files related to the application are downloaded to your smartphone (that means it will consume your internal memory/sd card, whatever you have), and if you plan to use that app, it will also consume the RAM, till the time it is active on your phone. If you plan to uninstall that app, it will surely no more consume any of your RAM, but it may be still using some amount...