Not sure about Voice Memos. I don't use my iPhone for that. However, if you can locate the memo in Finder from within iTunes (in iTunes, right-click on the voice memo, and then click on ""Show in Finder"), and it's on your hard disk somewhere, you should (in theory) be able to drag and drop it from that Finder folder to your Google Drive.
Also, keep in mind, I do not use Google Drive, but the cloud syncing services I do use, and have used, typically store a local copy of the synced folders on your system. So, if you're copying anything on your Macbook Pro over to Google Drive, you will basically end up with two copies of your files on your MBP (the original source, plus the copy in your local Google Drive folder) and a third copy on Google's storage in one of their data centers somewhere.