You can paste this code into your /app/views/client/bootstrap/structure.pdt
under the Blesta navigation:
<?php
if ($this->Html->ifSet($logged_in)) {
if ($client->two_factor_mode === 'none'){
?>
<div class="container">
<div class="row">
<div class="col-sm-12">
<div class="alert alert-danger alert-dismissible" role="alert">
<button type="button" class="close" data-dismiss="alert" aria-label="Close"><span aria-hidden="true">×</span></button>
<strong>Warning!</strong><br />
<p style="margin-top: 0px !important;font-size: 13px;">
It seems you haven't activated Two Factor Authorization yet? It's a security feature in which you provide two means of identification to log into your account.<br>
You can enable it <a href="//licensecart.com/customers/main/edit/" class="alert-link">here</a> under "Authentication".
</p>
</div>
</div>
</div>
</div>
<?php } } ?>
Change licensecart.com to your Blesta installation url. It should look like this: