Control · C-072 · Data & Data Governance

Prompt and log retention limits

Prompts, outputs and conversation histories are kept for defined periods and then deleted, by the organisation and by its providers, with deletion verified.

Control type
Preventive
Risks addressed
3
Audience
Heads-of · Practitioner
Frameworks
Article 19 · Article 5
Responsible AI domain
Reviewed
2026-11-11

What it does

It limits how long conversational data exists. A retention schedule states, for each class of prompt, output and log, why it is kept and for how long, and deletion is automated at the end of the period. The same limits are agreed with providers. Records management sets the periods with the data protection officer; the system owner is accountable for applying them. It is designed in at build and operates continuously.

How to implement it

  • Classify what is logged: full text, metadata, safety flags, audit records.
  • Set a period for each class from its purpose, and separate records that must be kept from those that need not be.
  • Prefer metadata to full text where it serves the purpose.
  • Automate deletion, including backups and derived stores such as caches and indexes.
  • Agree retention, review and training-use terms with each provider, and choose the settings that match.
  • Verify deletion by test, and review the schedule annually.

Evidence it operates

Design: a retention schedule covering AI prompts and logs; provider terms and configured settings. Operation: deletion job records; a test confirming that expired data is gone; store sizes consistent with the schedule.

Where it fits

Built at design and running through operation and retirement. It is the primary control for excessive retention of prompts and logs and supports unfulfillable data subject rights by leaving less to search. It works with AI record-keeping and audit trail, which defines what must be kept.

Limits

Retention pulls in two directions: accountability needs records and data protection needs deletion, and the schedule has to reconcile them case by case. Deletion at a provider is hard to verify independently. Data already used to train a model is not removed by deleting the log it came from. Short periods can remove evidence needed for a complaint that arrives late.

Risks this mitigates

Primary mappings

Excessive retention of prompts and logs Medium
Sets and enforces retention periods for prompts, outputs and histories. Prompts, outputs and conversation histories that contain personal data are kept indefinitely by the organisation or its provider.

Supporting mappings

Uncontrolled AI retirement Medium
Governs what happens to retained data. A system is withdrawn without managing dependent processes, retained data, model artefacts and continuing obligations.
Unfulfillable data subject rights High
Shorter retention leaves less to search and erase. Requests for access, rectification, erasure or objection cannot be met because personal data sits inside a model, or in stores that nobody can search.

Framework and clause references

FrameworkClauseTitle
EU AI ActArticle 19Automatically generated logs Log retention periods.
UK General Data Protection RegulationArticle 5Principles relating to processing of personal data Storage limitation.

How to cite

Axiom Verity (2026). Prompt and log retention limits. Reference Library, C-072. https://axiom-verity.com/controls/prompt-and-log-retention-limits. Reviewed 2026-11-11.