As of Thursday, anyone buying kegs of alcohol at grocery stores or bars will probably notice an identification tag attached to the container. It’s a way of helping liquor control authorities keep tabs on who’s buying the booze and who’s drinking the contents. Steve Shimmens, the Chief of Enforcement for the State Division of Alcohol and Tobacco Control, says better keg control might cut down on underage drinking. Some 70,000 tags have been sent to retailers throughout the state. The tags will remain with the containers until they are returned to the retailer. The tags will then be kept for a period of 90 days.