Future areas of application for mobile agents technology are open, distributed and decentralized networks, where Mobile Agents autonomously perform tasks on behalf of their principals . In this paper, we address the conceptual design of payments for and between Mobile Agents, particularly against the background of the Malicious Host Problem. We analyze the requirements on payment systems for Mobile Agents and give a survey on existing technical solutions partially matching these requirements. We then discuss a new concept that does not require Mobile Agents to hold secrets and that allows allocations of digital coins and agents even in an environment that contains Malicious Hosts. The concept is based on the principles of accounting systems.