Keeping records of your assessment and any control actions taken is very important. You may be required to store assessments for a specific number of years. Check for local requirements in your jurisdiction.
The level of documentation or record keeping will depend on:
level of risk involved,
legislated requirements, and/or
requirements of any management systems that may be in place.
Your records should show that you:
conducted a good hazard review,
determined the risks of those hazards,
implemented control measures suitable for the risk,
reviewed and monitored all hazards in the workplace.