Clockwork stores the collected data in a persistent manner.
The old data is automatically cleaned up after a specified cleanup interval, 30 days by default.
By default we store the metadata in a flat JSON file storage, located at
storage/clockwork. This is both simple and fast storage and doesn't require any particular PHP extensions.
Clockwork also includes an SQL storage implementation. SQL storage works great with a simple Sqlite database, but also supports MySQL and PostgreSQL. This can also be useful in a case where you need to use the collected metadata outside of Clockwork, eg. you could build an admin UI showing all requests to your application.
You can also extend Clockwork with your own metadata storage implementation, to learn how to do so, check out the "extending metadata storage".