This paper investigates issues of robot's personalization and long-term adaptation in human-robot interaction (HRI). It demonstrates the design and first technical implementation of a HRI showcase in the Robot House at University of Hertfordshire, UK. Here the central idea facilitating the long-term HRI is the creation of robotic companion, which provides various types of service to the user and can be personalised based upon individual needs. The personalisation can also be further enhanced through repeated interactions. The key component in the "mind" of the companion, which is highlighted in this paper, is the model of human semantic and episodic memory. The memory not only allows the companion to remember user's preferences for practical daily tasks, it also changes companion's behaviour in a longer time scale based on robot's perception of actual user input. Finally, implications of such a memory model in HRI are discussed. © 2010 The authors and IOS Press. All rights reserved.