Yes, you can still use other versions if the software isn't using online activation because if the activation server might be offline or discontinued, then you won't have the possibility to properly use the application.
If it just requires a name and password, then the application can be used successfully. If the application displays an error when you try to activate it, then it's using online serversб and there might be a problem with the serial numbers. In this case, continue with the trial mode if it allows you and go to Help > About to get the contact details of the developers.