Both the Moto Z Droid and Moto Z Force Droid on their respective US product pages show an offer for Free storage with Google Photos. Note that both these models will be launching as Verizon exclusives while the Moto Z (without the Droid branding) is not listed on Motorolas US website yet.
This news comes in not too long after an APK breakdown of the Google Photos app revealed that Google was supposedly going to offer unlimited storage for original resolution photos and videos if you had a Nexus device, surely to incentivize more people to buy such a device but now in this case, the Moto Z Droid models.
Heres the catch, the storage option will expire after two years. So if you store a ton a photos and your 2 years are up, Google will notify you that you need to start paying for storage or you need to download all the photos that are backed up.
The idea is to incentivize consumers to keep buying either new Moto phones in the future or possibly Nexus devices. Even if the perk lasts for a short time, it IS free.