Make PMPro Register Helper fields required for logged out users only.

is_user_logged_in_required.php

if(is_user_logged_in())
  $required = false;
else
  $required = true;
  
$fields[] = new PMProRH_Field(
  "company",              // input name, will also be used as meta key
  "text",                 // type of field
  array(
      "size"=>40,         // input size
      "class"=>"company", // custom class
      "profile"=>true,    // show in user profile
      "required"=>$required // set above
  ));