How to restrict node view to users by registration date?
You need use this hook https://api.drupal.org/api/drupal/modules%21node%21node.api.php/function/hook_node_access/7

So in your module you need code smth like this

function YUORMODULE_node_access($node, $op, $account) {
  $type = is_string($node) ? $node : $node-&gt;type;

  if ($op == 'view') {
    global $user; // get current user
    // check user register date
    if ($user-&gt;created &lt; $node-&gt;created) {
      return NODE_ACCESS_DENY;
    }
  }

// Returning nothing from this function would have the same effect.
  return NODE_ACCESS_IGNORE;
}