The Designer license of InSights Into Data is needed to create queries, dashboards, reports, etc. It is the full application and is what you will see in most of the videos and screen shots.
The Explorer License allows you to use the results of Queries, but not create them or run them. It is a great way of delivering the results of Queries, with the accompanying Grids, Reports, Dashboards, etc., to executives and others who could benefit from the results.
The Dashboard Viewer license of InSights Into Data is an application that can import and use Dashboards created by the Designer. You cannot create queries, dashboard, reports, etc. in the Viewer application. It is aimed at allowing other users, such as management, to explore the insights you create in the Designer application.
Monthly licenses (paid Yearly) are the normal license. These licenses enable you to use the program and have constant access to the latest versions of the program. This includes all major and minor updates. Your ability to use the program is valid as long as you have a paid subscription. You will be notified by the program 30 days before the expiration of your subscription.
The Lifetime license is offered as a way for those who do not like subscription licenses to be able to use the program and benefit from it features. It allows you to use the program forever, with a one main limitation. It allows upgrades until the next major version. However, you will not be able to upgrade to that next major version without purchasing either a subscription license or another Lifetime license. However, you can continue to use the version you have forever.