WooCommere Invoice Me For Selected Customers

WooCommerce Checkout without making payment rather select Invoice Me to make manual payment or payment later for known customers. This option is available only for selected and logged in customers. Invoice Me plugin is very helpful for virtual online market, digital product selling market etc. Online Documentation is here
http://rmweblab.com/documentation/plugins/invoiceme/
Demo here:
http://woocommerce.rmweblab.com/checkout/
user: demo
pass: demo