Google today alerted developers to a change in the Developer Distribution Agreement, but it will be families that really reap the benefit of the new language. Google is soon to launch the "Google Play Family Library," which will allow up to six people in a family (or their accounts, rather) to share apps they've purchased on Google Play.
The gist is that users will be able to buy an app once, then share it with others in their group. Developers will have to opt in to this feature, though, if they want previously purchased apps to be available for this. (And once they opt-in, they can't opt out.)
Here's the full language included in the new DDA:
5.4 You grant to the user a non-exclusive, worldwide, and perpetual license to perform, display, and use the Product on the Device. The user may include, but is not limited to, a family group, with a family manager and family members whose accounts are joined together for the purpose of creating a family group. Family groups on Google Play will be subject to reasonable limits designed to prevent abuse of family sharing features. Users in a family group may purchase a single copy of the Product (except in-app and subscription Products, which cannot be shared) and share it with other family members in their family group. If, in your Developer Console, you opt in to allowing users to share previously purchased Products, your authorization of sharing of those purchases by those users is subject to this Agreement. If you choose, you may include a separate end user license agreement (EULA) in your Product that will govern the user's rights to the Product, but, to the extent that EULA conflicts with this Agreement, this Agreement shall supersede the EULA.
This all takes effect on July 2, 2016, when the new DDA takes effect. Any paid apps purchased after that date will be eligible for family sharing.