What is the ruling on receiving a continuous monthly percentage of the profits offered by an investment company to whoever brings in new investors, as long as the investor remains with the company?

Originally, it is permissible for a company to give a commission to someone who brings investors. However, the majority of scholars stipulate that the commission must be a known amount. It is not permissible for it to be a percentage of the profits for the duration of the investor's stay, though some scholars do permit this.