The Meta Tag for Keywords is not as important as it once was. Google no longer uses it but it is still used by other search engine and every little bit counts so you should include it.
The <meta> tag’s keyword attribute is not the page rank panacea it once was back in the prehistoric days of Internet search. It was abused far too much and lost most of its cachet. But there’s no need to ignore the tag. Take advantage of all legitimate opportunities to score keyword credit, even when the payoff is relatively low. Fill in this tag’s text with relevant keywords and phrases that describe that page’s content.Bing Community Blog