Standard or Extended License for Mobile app UI Kit

I am about to buy a UIKit for a mobile app I am building. My question is, do I need the regular license or the extended license. I have read countless articles, forum topics, and none seem to give a clear answer on the difference between the two licenses. Let me give a little more information about what I am doing here. I am not going to sell the finished product, but will sell service related to it. So the app is not for sale, but the service I provide is. Could someone please help me understand this? Thank you so much…

As long as your users will be able to see/use the UI in your app for free, a Regular License is fine. If you will require your users to pay for your service in order to use the UI you need an Extended License.