In Jira Cloud terms, you buy an app by subscribing to it.
To find and try new apps:
- Select the Jira icon (
, 
, 
, or 
) > Jira settings > Apps. - Click Find new apps.
Once you're there, you can use the search and filters to find apps to help you get more done in Jira. To try or subscribe to an app, click Free trial next to the app.
If you don't terminate the trial within the trial period, a subscription for the app kicks in. Trials last for a month from the start of your next billing date. After starting a trial, you can stop it from the app administration page.
Although you can re-enable the trial within the original trial period, you can't try it again beyond the original trial period. At that point, you can only subscribe to the app from the Manage apps page.
Cancel an app subscription
To end a subscription for an app, click Unsubscribe next to the app in the Manage apps page. Canceling an app takes effect immediately. If you'd like to completely stop an app from appearing in the interface, you can uninstall it.