Prevent from multiple accounts

Hi,

I need to stop my community members to open more than one account in my site.

My community will soon be open to more than one country. And subscribers will be people, companies and other institutions.

Is there any way to verify identity and stop people/companies if they already have one account?

The email as unique field is not enough.

Any solution for this?

http://ww.wp.xz.cn/plugins/paid-memberships-pro/