The installation of the app is a standard procedure and is the same as for any other app for Jira cloud. You buy a cloud app by subscribing to it. First, you start a free trial, and then the subscription starts automatically after the trial period.
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- In your test cloud Jira instance, click the Jira icon, then go to Jira settings > Add-ons > Find new add-ons.
- In the search, enter "Issue History Collector".
- Click Free trial to download and install your app.
That's it! 
Note that 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 add-ons page. For more details, see Atlassian documentation.
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- In your test cloud Jira instance, go to Home > Settings > Add-ons > Manage add-ons.
- Locate Issue History Collector and expand its panel.
- Click Unsubscribe.
Canceling an app subscription takes effect immediately.