A mobile web app is an app that is accessed via any browser and is able to work across multiple platforms. A native app is a is developed specifically for iOS or Android and takes advantage of a broader range of features to deliver a greater scope of benefits to the client.
Your app will continue to run until the end of its current billing month then it will be removed and functionality will stop. Apps that are in the Apple App Store and/or Google Play will be withdrawn at this time.
The difference between the different plans is that the Basic & Standard plans are managed by the client and the Professional plan is a fully managed service.