PowerTip: Working with the Maximum History Setting
Summary: Learn how to increase the maximum history value.
How can I increase the number of commands that are stored in the Windows PowerShell command history?
Specify a new value for the $MaximumHistoryCount automatic variable.
In Windows PowerShell 3.0, the variable is set to 4096, but you can store up to 32767 history items
in the variable if you need to do so.