If your Logix5000 version 19 is licensed, you can download and install whichever version of Studio5000 you need to support the program you are trying to open. Your existing "activation" should be valid for Studio5000
Basically, RSLogix5000 and Studio5000 are the same animal, although there are some subtle differences such as the name, and the default application storage locations.
I'm sure you are aware that you need to install all software versions to support your hardware...