Activation process being skipped

I’ve observed that when I make updates to an executable with activation required (because the file has an expiration date), the activation step is omitted when the EXE file is downloaded to a computer that has a prior version loaded (with the same expiration date). Is this normal? If not, what might be causing this?

Yes, this is normal. Once activated, if you release a new version of your EXE, users should be able to upgrade without having to reactivate again.
If you don’t want that, you can change the application GUID, but in that case, all saves won’t be compatible with new version, so be careful.

So, as long as I don’t change the GUID, I can make updates and the users can take those updates and still use previous saves??

That’s like XLS Padlock. When we release updates, you don’t have to activate it again (unless your maintenance has to be renewed, but this is out of topic here).