Exempt users with a specific capability from being charged for sending private messages in BP Charges.

bp-charges-messages

/**
 * Maybe Charge Message
 * Exempt users with a specific capability from being
 * charged for sending private messages in BP Charges.
 * @version 1.0
 */
function mycred_pro_maybe_charge_new_message( $charge, $thread_id, $module ) {

	$user_id = bp_loggedin_user_id();

	// If user has a certain capability, exempt them from the charge
	if ( user_can( $user_id, 'edit_users' ) )
		return false;

	return $charge;

}
add_filter( 'mycred_bp_charge_new_message', 'mycred_pro_maybe_charge_new_message', 10, 3 );
add_filter( 'mycred_bp_charge_new_reply',   'mycred_pro_maybe_charge_new_message', 10, 3 );