Use PHP code to create custom user roles. Call it once?

I have the following PHP code in my wordpress site. I have noticed that when I disable the following code, those two user roles still exists both for current and new users.

/* ------------------------------ ADD NEW CUSTOM ROLES ------------------------------ */
add_role('barber',_('Barber'),array('read' => true, 'edit_posts' => true));
add_role('barber_shop',_('Barber Shop'),array('read' => true, 'edit_posts' => true));
/* ---------------------------------------------------------------------------------- */

My question is, do I need to call this code once, or should I always keep it running? Will it cause any issue in the future?