For $5 per month, users can enroll their device and then will have a $69 deductible for the 5X and a $99 deductible for the 6P. If you need to make a claim on an enrolled device, simply contact support (fi.google.com/account#support
Unlike Nexus Protect from the Google Store, which gives you 2 accidental damage claims over 2 years, Project Fi device protections gives you 2 accidental damage claims over any rolling 12 month period.
Since the device protection is billed on a monthly basis, if you leave Project Fi, you will therefore also lose the device protection.
For more information on how to enroll, please see this post.