whick plugin for wp_sitecategories

I can't for the life of me remember which plugin I need to install to get the wp_sitecategories to appear in my database - I've installed post indexer, tag-posts and global-site-tags and it still doesn't seem to be saving sitewide categories into the database...

I've had it on another install, but I can't figure out how I got it.. is there something I need to do?

Thanks,