A lot of people have been saying that Google has not used them for ranking pages for years and others who say that it is imperative that the keywords in the meta tag are relevant and match the content on the page for search engines to be able to qualify the page.
The short answer is this: many years ago Google according to Matt Cutts began disregarding the keywords meta tag because the keywords meta tag was so often abused. In the past, the keyword meta tags quickly became an area where webmasters could stuff often-irrelevant keywords without typical visitors ever seeing those keywords.
However, Google does support several other meta tags including the content “description” meta tag as the text for search results snippets that the searcher sees in a search result.
When building pages a good webmaster will always include a list af keywords that are relevant to the content on that page – it’s like having a summary of the page content for further reference when performing page optimisation.
It’s always possible that Google could use this information in the future, but as Matt Cutts says – it’s unlikely.