In Windows 8, you can find prefetch files at C:\Windows\Prefetch . These files have the extension .pf. The files are used by Windows to help applications start up faster. Metadata in the files tracks how often applications are used, when they are used, and which files the applications utilize.
Nirsoft has another great utility which allows you to view the content for these files. It's available for download here. WinPrefetchView will automatically find your prefetch files and automatically index their metadata.
As you can see this utility gives you a list of how many times an application has been used, and when it was last used in the columns to the right.