I found this plugin with a similar name. It is not free ($39.99), but it states, “Add custom registration…date of birth…”
http://wp-member.com/what-it-does/
WP-Members is open source and I’ve tried to keep it as easy to customize as possible. There is a discussion of customizing the fields for version 2.3.2 (current production version) here:
http://butlerblog.com/2010/09/27/adding-custom-fields-in-wp-members/
The process is a little simpler for the 2.4 public beta release as the install file has a toggle at the top of the code that you can change so as to force it to reinstall the settings without the need to delete the old. Version 2.4 currently available here:
http://ww.wp.xz.cn/extend/plugins/wp-members/download/
If all restriction is based on age, it should be a fairly easy process to implement. If you are restricting some content based on age and still want to restrict other content without condition, that would be possible, but more complex.
As far as the commercial plugin mentioned, I have no association with them – it a commercial plugin that is not open source. I won’t get into a discussion of whether they are better or not (hey – it is pretty feature rich, but they actually have a budget), or if encrypted code puts them at odds with the GPL, but I do have some pretty strong feelings on how they have hijacked the name of an existing plugin.
