On August 27th, Microsoft will start transitioning Xbox Live Gold Family Pack accounts into individual Xbox Live Gold accounts.
Family Pack accounts allow one primary account holder to share the Gold features with up to three other family members. Now all of these members will have individual Gold accounts for the remaining time on the Family Pack subscription plus three months.
Once this transition occurs, the primary account holder can no longer monitor the activities of the other Gold accounts, which was an appealing feature for parents. Microsoft has said that parental control settings will still be available, however.
This transition will take place alongisde the conversion of Microsoft Points to currency with the next Xbox Dashboard update.
[Source]