you can most certainly have beer, if you'd like.
just be cautious--with phen the idea is to make you cut back severely on food, and we all know what happens when one drinks w/out food!
I'd say try limiting it to 3 beers, preferably something somewhat healthy like miller/bud/coors light (michelob ultra is the best on calories/carbs) or something that's relatively low in calories/carbs, but fills you up too like a guiness (look up the nutritional info online.... you'll be surprised for such a heavy dark beer!)