hi John. lease commission is usually 1 month for every year. for multi-year contracts, commission for the following years (e.g. years 2 to 8 of an 8-year contract) can be negotiated to less than 1 month per year (usually half a month).
for renewals/extensions, generally the licensed agent is entitled to a commission. you should consider the service rendered by the licensed agent in securing the renewal/extension. in this case, commission can be 1 month/year or less than 1 month/year, depending on mutual agreement of the lessor and licensed agent.