I totally deleted the Product Key
Ok, but the app will still be activated because your app on the machine doesn't know about the fact that you deleted the key (and it won't know about it until it recontacts the server).
tried using TurboActivate.exe to "reactivate" the application, figuring it would ask me for a product key. It just tells me that the activation was successful
Because TurboActivate.exe just calls IsActivated() and since the machine is still activated the TurboActivate Wizard will say you're still activated.
When I try to run the application it is STILL running in the middle ("Advanced") feature set and if I try, on numerous occasions, to run TurboActivate.exe to "reactivate" or "deactivate" the application, it still tells me the activation was successful.
To deactivate call TurboActivate.Deactivate() in your app.
In the future, when you're changing custom license fields, you have to realize that the change isn't immediately reflected on the customer's machine. You (or the customer) has to force it by re-activating (inside your app, not using the TurboActivate Wizard) or the new fields will be downloaded in X days if you're using IsGenuineEx().
See: Changing fields & getting the changed data in your app.
Does that make sense?