Please have a look at the section "Refreshing Expired Tokens" in the Podio Authentication documentation. When you get your access token, you also get a refresh token and the
expires_in property shows the number of seconds until the access token expires. You should use the refresh token to renew your access token prior to expiration. If you're using an SDK, it may have auto-refreshing of access tokens (e.g. podio-rb).