Can subscribers be converted into WordPress Users?

Hello:

I have a client who needs to have people who subscribe using this plugin converted into WordPress Users (with the role of Subscribers, so the people can be found under Users >> All Users). I don’t see that this is a function of the plugin, am I wrong (and it is a function that needs to be turned on) or is there a way to do this (with another plugin, or some code, etc). I’d love any thoughts the developer or others have for this issue. Thanks in advance.