How can I get log retention enabled in GCP Stack-driver. I haven't found any document for configuring log retention. I can see export option in logging section and log ingestion.
NOW, it is possible, see this post bellow (edited)
Previous answer:
Logging retention is 30 days and it is not configurable, you only pay for the storage
Stackdriver Logging allows you to retain the logs for 30 days, and gives you a one-click configuration tool to archive data for a longer period in Google Cloud Storage.
https://cloud.google.com/logging/
But you can create a sink for you logs and store them in Big Query or Google Cloud Storage (or both of them)