This document lists requirements that are specific to applications developed with the Street View Static API. Note that use of the Street View Static API is governed by the Google Maps Platform Terms of Service.
Pre-Fetching, Caching, or Storage of Content
Applications using the Street View Static API are bound by the Google Maps Platform Terms of Service. Section 3.2.3(a) and (b) of the terms states that you must not pre-fetch, index, store, or cache any Content except under the limited conditions stated in the terms.
Note that the panorama ID, used to uniquely identify a Street View panorama, is exempt from the caching restriction. Therefore, you can store panorama ID values indefinitely. Panorama ID values are returned in the pano field in Street View Static API responses.