Symptoms

Currently we are using server A and database B (2005 sql) combination with a K2 key license.

Now we have upgraded the database B (2008 sql) but as a host server we are not using server A instead we are using server C.
 

Diagnoses

The license key doesnt work here on the new server C.

 

Resolution

This is expected.
By default each Server will have its own unique Machine key which gets generated/created according to the hardware and other specifics.

Since your machines keys don't mach and your previous servers license was created according to the machine key provided, you cant just copy a license over.

Please request a new license using the new Machine key for server C. This will resolve the issue.