In the Presenter Menu go to Help > About Adobe Presenter. A dialog will open showing your version of Presenter.
In the same Help menu, you should see a Check for Updated option. That will call out and look for the latest updates. Presenter's updates need to be installed sequentially, so you may need to run the Check for Updates function multiple times to ensure you have all the updates. Once it no longer finds updates for Presenter, you will be on the most current of whatever version of Presenter you are running.
The following are the most current versions of Presenter:
Presenter 7: 7.0.7
Presenter 8. 8.0.1 build 260 (despite the latest update being 8.0.2, I show 8.0.1 still. 8.0.2 may be a 64 bit update...)
Presenter 8.1 (ASA and subscription customers only): 8.1 (I think)
Finally, here is a link to the available updater executable files. If you don't want to run through the Adobe Updater, then you can download the updates directly from here: http://www.adobe.com/support/downloads/product.jsp?product=153&platform=Windows