Adverts can be displayed for a restricted period based on the number of times they are viewed on the site.

This figure controls how many times the advert may be displayed (not clicked by displayed) before it is automatically disabled.

In general this corresponds to one of several ways to sell advertising and works in conjunction with any date-range set for the display of the advert.

In other words: if both a number of views and a date range are both set - whichever limit is reached first will cause the advert to become disabled.