miji.beA data retention period defines how long a web analytics tool or service keeps collected user data before automatically deleting or anonymizing it.
The growing focus on data retention stems from privacy regulations like GDPR (EU General Data Protection Regulation) and Japan's Act on the Protection of Personal Information. GDPR states that personal data must not be kept longer than necessary for its purpose, making indefinite retention a legal risk.
In Google Analytics 4 (GA4) you choose the event data retention period in the admin settings. As of August 2026 a standard property offers 2 months or 14 months, while Analytics 360 adds 26, 38, and 50 months. Leave it on the shorter setting and data older than that is progressively lost. The other pitfall is what the setting actually covers: it applies to explorations and funnel reports but not to the standard aggregated reports, so numbers can still appear in a standard report while an exploration comes back empty. To keep data longer, set up the BigQuery export. Google states that you own the data once it is exported, so it can be handled separately from the retention setting on the GA4 side.
Data retention periods for URL shortening services vary widely. Some free plans delete click logs after 30 to 90 days, while moving to a paid plan extends retention on some services. For long-term campaign analysis or trend comparisons, choose a service with longer retention or regularly export data as backups.
When designing retention policies, balance analytics needs with privacy. Marketing analysis typically requires at least 13 months of data (for year-over-year comparisons), but personally identifiable data (IP addresses, cookie IDs, etc.) should be deleted or anonymized within the minimum necessary period.