This seems almost identical to the real estate agent model. Real estate agents (similar to travel advisors) work for real estate brokers (similar to host agencies), and an agent must work for a broker to do sales. The commission is often split between the agent and the broker.

Is there a minimum amount of business (# nights per month or revenue threshold) to work for a host agency? E.g. if you live in hotels full time and sometimes book for friends would that meet a relevant threshold or is much more than that required? I was looking into being a part-time real estate agent but the required minimum number of transactions is actually substantial (i.e. hard to do part time), even if you sign up with an online broker who has less strict requirements.