Apple has provided the ability for families to share apps purchased between them for a while. Google will add support for the "Family Library" feature to Android on 2nd July.
Up to six family members will be able to share app purchases between them across multiple Android devices. Free apps are not affected.
It probably won't be only apps that can be shared, in time Google may add support for sharing purchases of music, books and other purchased content to bring the features into line with Apple's offering.
How are developers affected?
If you have a paid app available in Google Play, purchases on or after 2nd July will be automatically enabled for sharing with up to six family members. As a developer, you can opt out of this feature in the "Family Library" section under "Pricing and Distribution" in Google Play.
If you want apps that were purchased before 2nd July to be available for sharing, you'll need to go into Google Play and check the box, as described in the Google documentation. Google recommend you make past purchases available in Family Library if your app won't be opting out of the feature.
Should you opt out?
Whether you should opt out of the feature really depends on the target audience of your app and your business model. Careful consideration should be made before opting out of this new feature. We expect the majority of paid apps would benefit from enrolling in the programme, as is the default behaviour on Google Play.
It's a big selling point of your app, especially if it's targeted at children or families, or already participates in the "designed for families" discovery experience. If your app is available in Family Library it'll be included in the app listing in Google Play, so many users may take that into acccount when deciding whether to buy your app.
If you do decide you're going to use Family Library, you should definitely opt-in previous purchases so families who have already bought your app and want to take advantage of the new sharing features can do so.