Hi Ellen,
This does require a subscription but based on the products and license your company has, you might be entitled to use it.
As you can see in the screenshot below , This is part of a package.
When you log onto ServiceNow store and find the plugin, it will tell you if you have the subscription for it or not, under the 'Your Subscription status'.
Alternatively, You can reach out to your ServiceNow Account Manager and they will be able to clarify all of this.
