I’m sure you’ve noticed in your analytics reports that there are now large numbers of visitors to your site that come through with the keywords (not set) and (not provided). These are the visits that came from people who were logged into their Google Accounts.
It used to be, you could see all the keyword data for all the visitors to your site. Now you can only see the keywords via Google if those visitors came through some sort of paid search, or the URL was specifically tagged with a keyword tag.
This creates holes in the data available to website owners each month when a large percentage of their visitors come in tagged with (not set) or (not provided).
You can, however, get this information for any advertising campaign you are running. The (not set) and (not provided) tags are from visitors through the natural (or “organic”) search results and not any paid advertising.