Those widgets are coded to remove HTML tags from those fields.

You can change that by editing the widget file.

pricing_tables_widget.php located in /inc/widgets/ directory.

On line 85 change,

$instance['feature_1'] = strip_tags($new_instance['feature_1']);

to

$instance['feature_1'] = $new_instance['feature_1'];

You can do the same for the rest of the feature fields.