It allows user to access any file or application but for a limited number of tries,

                 limited number of accessing, or limited date.

                         Best against crackers, hackers ...                          

                  For now-a-day business trends on the Net, this is the best way for

                  letting users check your products for later sale. It's a restricted access

                  where u can check things for free and you buy when you are convinced to.