ERROR "Licensing for this product has expired" =

Caused by not setting your host file, previous trial has expired or previous
version has left key in registry.

Soloution 1;

Go to the HOSTS SET-UP folder and follow the steps there.

Solution 2;(try A then check app then B then check the app);

A Do the steps in the ADOBE LICENCE RECOVERY TOOL.

B 1. Delete;
     Program Files CommonFiles Adobe Adobe PCD 
     Program Files CommonFiles Adobe caps 
     Program Files CommonFiles Adobe backup 
  2. Restart app and enter a serial.

Solution 3;

Go to the CS5 LICENCE RECOVERY folder then the DLL FILE folder and copy the
32bit dll file and replace each instance of that dll file in your adobe programe 
directory, then if you have 64bit copy the 64bit dll file and replace each instance
of that dll file in your 64 bit programe directory.

Soloution 4:

Go to the CLEAN INSTALL folder and follow the steps there.