“Candidates can't exceed five GMAT exams within a 12-month period or the eight lifetime GMAT exams (lifetime limit updated November 2016).”
There was previously no lifetime limit. Now there is. I guess this means that GMAT prep instructors will not be able to keep on taking GMAT. Most applicants never take it 5 times let alone 8 times. However, if someone applies for MBA programs and the comes back to it a few years later, they could easily take GMAT 8 times. Fortunately, there is the GRE!