AWS.service is a Cocoa service module. It runs only in the background. You do not need to launch it or start it or exit it: the system takes care of all of that for you. AWS.service will make selected text anywhere on your desktop capable of invoking a service from a resource on the web.
All you need to do to make AWS.service work is drag it to the right location and log back in. See below for details.
AWS.service is one of three modules in the ACP Web Services; the other two, AWSManager and AWSBrowser, are available at no cost through a separate download.
OS X version 10.2 through the current 10.10; the AWS.service module takes very little disk space; there are no special memory requirements. Once you've installed the module, everything is automatic: once you log back in, you can configure things from your Services Preferences, and then you'll see your new items on your Services menu.
Do this first from a command line:
$ mkdir ~/Library/Services
(It's OK if you get the response that the 'file exists'.)
Drag AWS.service to ~/Library/Services and restart your computer.