A track can be public (playable for anyone) and private (playable only for members of the organization the track belongs to. A track invite is unique link that lets people play a private track, and you can add limits to track invites links to prevent abuse (you can't add limits to public tracks).
If you create an invite link, learners can use it to claim the track. Once claimed, a track is added to the learners Study Room, so they can return to the track later.
Track invites are part of the organization settings in the web console (currently, there's no way to manage track invites using the CLI)
You can add limits to a track invite link:
Limit the number of times the link can be used
Set an expiration date and time for the link to stop working
Require learners to create an account (disallow anonymous access)
Require learners to have an account, and create a list of allowed emails (or an entire domain).
Once a learner claims an invite, they have forever access to the track, unless you add limits:
Limit the number of plays of a track
Make the track available for a learner for a limited time (track expiry)
If you delete a track invite link (or when the link expires), learners that already claimed the invite still have access. Set track limits if you want access to expire.
If you edit a track invite, changes will not apply to tracks that have already been claimed. For example, if your track invite provides learners with forever access to the track (no track expiry and unlimited plays), the track access of learners that claimed the invite will not be revoked if you add track limits to the invite link later.