There's not a command for looking at a full history of all previously associated clients (in the same output window) within the controller itself. This would be a function of NSight. Either the CLI or GUI will obviously give you a listing of currently associated clients though....along with a detailed list of various metrics.
But, what you can do is look at a single client's association history, one at a time, using the command syntax:
sh wireless client association-history (Info also shown in the GUI)
The results don't include an actual Duration column, but it does have a Delta Time...so that you can see each time it was associated and the time period between associations.