How to Share Excel 2013 Files
Select the Allow Changes by More Than One User at the Same Time check box on the Editing tab.
By default, Excel maintains a Change History log for 30 days. If you wish, you can use the Advanced tab settings to modify whether Excel maintains this Change History log (necessary if you want to reconcile and merge changes) or to change how long the program saves this log.
You can also change when changes are updated, how conflicts are handled, and whether your print settings and data filtering settings are shared.