A dedicated IP is a unique internet address dedicated to a particular hosting account. A dedicated IP is an IP which is used only by a single user or account to send emails and no other user will be able to send out emails from this address. Only that user’s email is sent from that IP, so the volume of email sent from that IP and the reputation of the IP is determined only by the email sent by that user.
Only business hosting accounts are eligible for dedicated IP addresses. A dedicated IP acts as an identity for your business.
So, If you send out a high volume of emails regularly and use a third party application/script then you most definitely need a Dedicated IP address.