Meta tags are no longer valued in Google anymore, Bing gives negligible importance but in all, meta tags today are used only to index content based on its LSI keywords but NOT rank the keyword accordingly.

Keyword tag is not important, but Title and description tags are important.

Yes some search engines are not counting keyword tag but you should use it on your web pages.

Though meta keywords tag and meta description tags are not the main factor search engines consider when ranking sites, they should not be left off the page. A meta description tag is supposed to be a brief and concise summary of your page's content. A meta keyword tag is supposed to be a summary list of the most important words on your page. They were both proposed in order to make using the web easier. Unfortunately, webmasters over the years have abused meta tags so much that search engine creators have had to de-emphasize their importance in their algorithms.