The Google Analytics Data Retention controls give you the ability to set the amount of time before user-level and event-level data stored by Google Analytics is automatically deleted from Analytics’ servers.

User and event data retention

The retention period applies to user-level and event-level data associated with cookies, user-identifiers (e.g., User-ID) and advertising identifiers (e.g., DoubleClick cookies, Android’s Advertising ID, Apple’s Identifier for Advertisers).

You can choose how long Analytics retains data before automatically deleting it:

• 14 months
• 26 months
• 38 months
• 50 months
• Do not automatically expire

When data reaches the end of the retention period, it is deleted automatically on a monthly basis.

If you change the retention period, then any affected data is deleted during the next monthly process. For example, if you change from 26 months to 14 months, then any data older than 14 months is deleted during the next monthly process.

Whenever you modify the retention period, Analytics waits 24 hours before implementing the change. During this 24-hour period, you can revert your change and your data will be unaffected.

Reset on new activity

Turn this option ON to reset the retention period of the user identifier with each new event from that user (thus setting the expiration date to current time plus retention period). For example, if data retention is set to 14 months but a user initiates a new session every month, then that user's identifier is refreshed every month and never reaches the 14-month expiry. If the user doesn't initiate a new session before the retention period expires, then that user's data is deleted.

If you do not want the retention period for a user identifier reset when that user has new activity, turn this option OFF. Data associated with the user identifier will be deleted automatically after the retention period.

Set the options

You need to have Edit permission for the property to set these options.

1. Sign in to Google Analytics..
2. Click Admin, and navigate to the property you want to edit.
3. In the PROPERTY column, click Tracking Info > Data Retention.
4. User-data retention: select the retention period you want.
5. Reset on new activity: turn the switch on or off.

Data retention and the Users metric

As of February of 2018, we added the Users metric to many additional reports. Because this metric is new in these reports, we do not have aggregated data for this metric for all of these reports for all time. This may impact your historical reporting: you may see zeros for User counts prior to the time for which we have aggregated data for that metric.

We began aggregating data for 360 properties on May 1, 2016, and for standard properties on Sept 1, 2016.

This does not affect the Audience Overview report, however, which has aggregated User data for a much longer period of time.

* Nguồn: Google Analytics