Yes. The one-time, in-app purchase to activate/unlock our Plex for iOS app is compatible with Apple’s Family Sharing functionality. To make use of it:

1. The iOS device must be running iOS 14.0 or newer system software
2. Your Apple ID must be a member of a “family” in Apple
3. The one-time, in-app purchase must be made by the “admin” account for the family
4. Purchase sharing must be enabled for the family admin : Purchase sharing
5. When signed in to your member Apple ID, use the Restore Purchase button either on the activation screen or under Settings > Account in the Plex app

Related Page: Unlocking or Activating Plex for iOS
Related Page: Apple: What types of content can I share with Family Sharing?
Related Page: Apple: About in-app purchases