on a shared hosting account. If that's the case, the host will maintain the hardware and security of the server, so there's nothing for you to worry about.

That said, you are responsible for the security of your website. WordPress websites in themselves are pretty secure, so you'll be OK there, however by installing third party plugins you run the risk of opening yourself up to vulnerabilities if the plugins are not securely developed. I would only trust plugins that have lots of downloads, good rating and are regularly updated.

Lastly, I recommend you make regular back-ups of your website (the files and the database). If you do that, should something happen to the site, you can restore it anytime. Since you don't have any confidential information on the site, such as personal addresses, credit card numbers, etc, you don't really have any data that would warrant real-time protection.

Short answer: no, I don't think you need a security service in your case.

~Sovereign