Since writing about S2 Member a few years ago, a lot has changed in the WordPress membership plugin scene.
For starts S2 Member have stopped updating the plugin and responding to support request. The parent companies website is also offline.
Building your membership site out with a an abandoned plugin is a huge risk, instead I recommend you use any of these plugins-
Both of those plugins are leaders in their class, provide excellent support and give you everything you need to create a solid membership site.