When you buy the Motorola CPS is it downloaded or a CD is shipped to you?
You'll get the current version shipped to you. I just renewed our subscription to the Pro Series CPS and got a shipping notice so I'll be watching for a FedEx delivery this week.
Then when the next version is released, you will be able to download it right away.
Just understand that they won't send you a notice of a new version. It's up to you to discover that and there are several ways to do so. The easiest is to log into your MOL account every few weeks and check the info releases on the home page. If you see a new version of your CPS listed, just click on it and it will take you right to the download. That's a very good reason to explore MOL a bit and get used to how things happen there.
Some forums like the batboard and p25.ca generally experience a post or a new thread when a new version of some CPS's are released. To some extent, that depends on which CPS it is as there is more interest in some than others.
The bottom line is that you have to be a bit proactive to stay current.