Use Trial Software Forever

1.Uninstall the application
2. Go to Start Type "Regedit".
3.Go to HK Local Machine > Software > Your Software name. Delete the Key.
Do this for HK Current user if there exists a key of that software.
4.now you have to go to run type %temp% and delete all the files which exists,They are just some temporary files,It wont matter much.
5.Go to Users > Username > Appdata and then Check all 3 directories that is "Local", "LocalLow", "Roaming" for your software entry. Delete that.

Now all you have to do is re-install the program and enjoy the evaluation period again!