AdBlock Premium is not a Windows or MacOS application like Microsoft Word or Google Chrome. AdBlock Premium is a browser extension, a little piece of software that extends Chrome's capabilities. That means it won't appear in the list of apps installed in Chrome or the list of Windows or MacOS applications installed on your computer. The only place you will see it is in the list of extensions installed in Chrome.
Here's how to tell whether AdBlock Premium is installed. Open Chrome's extensions page by entering chrome://extensions in the address box and look for AdBlock Premium in the list. It should look something like this: