It is really easy to be tempted to use the membership plugin for wordpress when you need something like this and you already installed the blogging problem. The problem is that there are some facts that you might not have known till know. Unfortunately, all specialists agree that the plugins that can be downloaded are going to be really easy to hack and this is something that nobody actually wants.
If you already installed the membership plugin for WordPress, you need to seriously consider changing this and using one of the much better PHP based options that are available on the market. You are going to have a lot more security and the main benefit is that the experience will be a lot better for absolutely all your members. In addition, you can also include newsletters, forums and whatever you might think of. On the whole, this is a much better solution that you should seriously consider at all times.