Google Play's Family Library with app and game sharing goes live July 2, 2016.
From the relevant post on the website Android Police:
Family Library and sharing have been a long, really long, time coming on Google Play. In his different app teardowns, Cody has repeatedly discovered strings pointing out to the feature coming to Play Books, Play Movies, Play Services, the Play Store, but up until recently, the only Google entity that had benefited from any kind of family sharing was Play Music and its Family Plans.
But at this year's Google I/O, Google announced that Family Library was coming to Google Play app and games purchases with the new changes taking effect on July 2nd.
What has already changed though are the terms of the Google Play Developer Distribution Agreement. A new section 5.4 explains how a family group, with one manager and different members, can purchase the product once and share it with other members of the family. So starting July 2, any purchases you make on the Play Store will be available for sharing with your other family members.