This paper discusses longevity issues of metadata in the Linked Open Data (LOD) environment, where metadata is transferred and shared on the open Web as a digital object. The fundamental issue of metadata permanence is to keep metadata interpretable by machines and humans over time. The goal of this discussion is to clarify risks in permanence of metadata and issues in the long-term management of metadata and metadata schemas in the LOD environment. This paper discusses metadata longevity from a few different viewpoints in order to clarify the requirements of metadata permanence in the LOD environment, which are different from those in conventional document-like object environment or database-centric environment. Longevity of metadata is, in other words, the temporal interoperability of metadata. This paper uses the Metadata Application Profile methodology supported by the Dublin Core Metadata Initiative (DCMI) and DCMI’s layered model of metadata interoperability to understand the nature of metadata in the LOD environment. Then, this paper discusses metadata longevity based on a set of facets of metadata entities such as metadata schemas. Finally, it briefly discusses issues to use provenance description of metadata schemas and metadata schema registries from the viewpoint of long-term maintenance of metadata schemas