Back in 2009, Matt Cutts (head of webspam at Google) announced that Meta Keywords it’s not used anymore in ranking websites. These keywords were an internal technique, available to anyone. This and the fact that all the people used Meta Keywords to spam the search engines made Google remove it from its ranking factors.
Knowing this, please stop promoting/buying SEO services which includes Meta Keywords research and updates. The time used for this is useless and you will end up paying for nothing.