Any plan to support Friendly Captcha ?

I hadn’t planned on it. Generally, I abhor captchas. They are usually employed as an anti-spam device, and at that they fail miserably. There are far more effective ways of combating registration spam than captchas.

It might be something that I can add – I won’t commit specifically because you’re the first (and currently only) person to bring it up. So I’m not sure what the level of demand is for adding it. But I will consider it and look into it.

The other part of the answer would be that, depending on your level of technical ability, the plugin has action and filter hooks in it to provide for customization – just like WP does. You could use the wpmem_fields filter would probably give you the ability to incorporate the captcha into the form. The wpmem_pre_register_data action would allow you an action hook point to validate the captcha result (to either throw an error or allow registration to proceed).