Laura Craft is available for purchase on each new Live Event, as outlined in the description on the pack before making the purchase.
She's a busy girl and spends a lot of time collecting various resources for each event. This type of pack is a new thing we're trialling - in fact, Laura is more of an NPC (non-player character) than a pack, so she's a bit more temporary!
She doesn't quite work like the clothing you put on your Sims day-to-day. Each event is a different event, so you'll need to re-hire (purchase) her.
The game team have also listened to your suggestions and made adjustments in this update to make Laura more effective - she now collects more resources and spends less time doing so.