The tracks feature is available during FITR's 30-day free trial and is included in the Professional Plan. If your free trial ends and you do not upgrade to the Professional Plan, you won't be able to edit Tracks.
To continue using this feature, you'll need to upgrade to the Professional Plan by going to Settings > Subscription. If you decide to downgrade from the Professional Plan, you'll lose access to Tracks, but all your Tracks and content will be safely saved and ready for when you upgrade again.