Is there a way to list when workflows were last run? Trying to cull some old workflows and would like to know when they were used last
The easiest way I have found is to just perform a search. Workflow keeps reporting data based on the setting in the Workflow Administration Console under {ServerName}\Server Configuration\Advanced Server Options. Ours is configured to keep 1 year's worth of data, so when we perform a search with no date parameters and nothing is returned, we know that it hasn't been run in the last year.
The default retention for full instance details is 30 days. So that is what you would get with search. The settings for retention are in Advanced Server Options in the admin console. Extending the retention may have an impact on the size of the SQL database.
We retain information on whether an instance of that WF ran for 365 days by default. This info is used when you generate a statistics report (from the WF Designer or WF Admin Console). It won't give you the exact date when an instance ran, but it will give you counts of instances run in a given timeframe (per workflow definition). You can tweak the timeframe to get an idea how long ago the last run was. Same as for search, if the workflow is not listed, no instances were run within the last year. Retention settings for this data are also in Advanced Server Options. Since this is aggregate data, extending its retention has less of an impact on the size of the SQL database.