Meta keyword is dead. Most modern search engines don't value it any more - they dynamically generate keywords from page descriptions, which makes more sense too.
3 things search engines value most are:
Page title - meta title for product/category in alicommerce 2.0
Keywords in URL - human friendly URL support in alicommerce 2.0
The first H1 tag in the page - product/category name in alicommerce 2.0