Make a note that this is the software KEY not the actual app. You have to download the app separate, which allows for you to do the full setup and see if it works with your company's exchange or not. Then you will buy the key on top of the free regular app (free trial that is) and it will unlock all of the features permanently.
From Amazon Description:
Exchange By Touchdown is the ultimate productivity tool for the hard-working smartphone user. Use this app to connect to your company's Exchange Server with secure access to your corporate e-mail, contacts, calendar, tasks, and notes. With TouchDown, you receive your company e-mail immediately using push technology. You can also send e-mails, address appointment requests, edit your contact list, and manage your tasks and notes. Try out this application for a full 30 days and decide for yourself. If you want to activate the full version of Exchange By TouchDown, simply upgrade by purchasing the Exchange By Touchdown Key app.