Persisted Access is mentioned here as a remote method. On that page you can also find an explanation as to why Persisted Access was introduced by viewing the article How the Pandemic has changed Authentication and Access
We are persisting institutional authentication in a user's browser for 180 days since their last institutional access. When a user accesses a page, we look first for current institutional authentication (for example accessing via an institutional IP range, or a login via SAML). If no current authentication is found then we return the most recently persisted account number, which the user will have persisted against their session from their most recent authentication against an account.
Non institutional IPs can show on reports with usage. If a user has authenticated against an institutional account, and then in the same session on their browser accesses from a different location, then their session IP will change. This means a user accessing from home, for example, could have their home IP returned against an institutional authentication. Their authentication has persisted, but their location has changed, therefore picking up an 'unknown to the institution' IP when accessing the content.