Hi!
If you mean product tags (WooCommerce or other ecommerce), you can select them on the custom taxonomy terms selection list: http://i.imgur.com/UX1pqnf.png
However if you mean post tags, it’s not possible in the current version yet, but it’s under testing for the upcoming version. It was implemented in earlier plugin versions, but it raised huge performance problems so I had to remove it.
I was finally able to work out a better solution, so it’s coming back with the next release in 5 days.