 <p>There's little interest in storing the <code>directory_service</code> object, because it is created without making calls to external APIs.</p> <p>What you should store is the <code>http_auth</code> object, as this one can be costly to generate.</p> <p>In addition, tokens from service accounts can only be requested a certain number of times per second. I do not think the exact limit is documented somewhere but if you try to generate too many tokens from the same service account at the same time you will get a <code>Rate limit exceeded</code> error.</p> <p>The good practice is to store the tokens in some shared storage service. It can be memcache or the Datastore. The Google API client comes with <a href="https://developers.google.com/api-client-library/python/guide/google_app_engine#Storage" rel="nofollow">an App Engine specific <code>StorageByKeyName</code> class</a> that you should use. It is backed by the Datastore and uses Memcache as an optional cache layer.</p>