When it comes to apps in the App Store, if there is no cost, you will see Get. If there is a cost to the app, it will show the cost in the button instead of Get. Understand also, there are a number of free apps that have what are called in-app purchases, which are cost items that can enhance an app, or provide additional features. There are also many free apps that come with a subscription service, and you get a week or so for free and then a recurring subscription. This subscription will begin with no intervention from you, so if you don't want the subscription, you have to cancel it. This support document may also provide you with some additional information. Download apps and games from the App Store - Apple Support