Solution Design / Feasibility Answer - Wifi Access via App

I require a high level solution design/feasibility answer to explain how I would design an app that solves the following problem. Currently, we operate a private wifi network and give monthly access to users after they have purchased different packages of wifi access and can surf the web at different speeds for up to 30 days. My problem to answer is how do I design a mobile app (IOS and Android) that will give access to our network once the user is validated to have an active monthly package but the access is granted (after they are validated) once they have downloaded and activated the app. For example, on the app there might be a button saying connect now and then the app can stay in the background and allow users onto the network. The secondary point of ensuring access is granted via the app is that once the app is active, we can then push notifications and provide other value added reasons why the user would download the app to 1 access the internet and 2 access additional value added services that we would provide. I don't require the actual solution at this stage, but for now am validating that there is a solution to my problem. Thanks.