Software as a Service (SaaS) – This means that you buy a software as a service on a subscription and that it is provided by the supplier instead of a license and that you yourself need to run the software locally. Usually no client is needed at all but the service runs in the browser, but sometimes you need to install a thin client. SaaS services have significantly more complicated business models as you need to calculate the customer’s LTV and CAC to know if your marketing investment is effective or not.