One may wonder why it is important to know the number of concurrent users while estimating the hardware for Qlik. However, a Qlik consultant should be aware about Qlik reserving approximately 10 percent of the RAM per application for every concurrent user. This RAM is allocated when user opens any application hosted on Hub. For example, if a sales application is consuming 2 GB of RAM and there are 10 concurrent users, the RAM needed will be  4GB (2 GB+ 200MB*10).

So the number of concurrent users plays an important role in deciding the RAM requirement for the Qlik hardware.