</p<> By changing the value there you can avoid the default which is to remove associations after 60 days.
</p<> (The default is for performance reasons but means that although the information about the workflow is still in the tasks and workflow history lists, the association between the workflow and the item has been purged from the database.)
</p<> This option is located at
</p<> Central Administration > Operations > Timer Job Definitions> Workflow Auto Cleanup