What is the 'keep warm' function and how long does it last?

All three warmer programmes have an integrated 'keep warm' function that automatically starts at the end of the heating cycle or after manually stopping the programme. The keep warm function stops automatically after 45 minutes, signalled by 3 long beeps. When using this function, the Bottle Warmer Basket and Bottle Warmer Cover should be left in place. (Page 7)