To purchase the listing description service, go to the "Services" tab on the menu (https://app.rankbreeze.com/services) and click "Learn More".
On the page that opens up, scroll to the bottom to select your order based on the number of listings you want optimized and checkout.
Note - The Listing Optimization Service is an add-on service that attracts a 1-time fee. The charge does not include the monthly/quarterly subscription fee which gives you access to the Rankbreeze software.