In the end, Feng Bujue did not purchase the beer. After all the quest tab said it had to be an 'ice-cold beer', if he returned with a warm one, he might not complete the mission. Furthermore, even if he wanted to buy the beer and then directly go and finish the mission, he had to find a route that would take him back. The route that he took to come to the ground floor was one-directional and he was too weak to bounce back up the 'corner' so he had to find another way. Therefore, Brother Jue temporarily ignored the vending machine and moved his search somewhere else.