PL7 Installation problem

Hi all,
I am facing problem about installation of modicon PL7 version 4.3 softawre . I had 21 days trial pack of this software.and i was installed this software once. but after 21 days whan i am trying to reinstall this software . this software not install .so please any one help me .

umm sounds like you should format your hard drive or hack up your registry and program files? Prehaps maybe buy a licence?