Event level history leaves a property through BigQuery. Create a Google Cloud project and turn on the BigQuery API, then in Analytics go to Admin then Product Links then BigQuery Links and click Link. The person doing it needs Editor or above on the Analytics property and OWNER on the BigQuery project. Pick Daily, which writes one file a day holding the previous day's events, or Streaming, which is continuous; Analytics 360 properties also get Fresh Daily. A standard property is capped at 1 million events a day on the daily export, and a property well over that has its daily export paused, with the missed days never reprocessed. Data streams and named events can be excluded during linking to stay under the cap.
What it holds
Web and app events with their parameters, user and session identifiers, traffic source and device detail.
Find the size
Analytics prints no storage figure. The countable is event count: the daily export writes one file per day and a standard property is capped at 1 million events a day, so quote the row count of the events_ tables in BigQuery. Read Admin then Data collection and modification then Data Retention first, because event level data is kept for 2 or 14 months and nothing older is in the property to export.
What to enter on the form
Google Analytics in records, and the year your company started using it. Seller form