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