What happens after the user's activation key expires

[gdgsupport]

No, the EXE itself won’t show a warning. But you can implement it in your workbook with VBA. XLS Padlock provides a VBA API that lets you get the number of remaining days.
See working code here:

Retrieve Expiration Date

Normally, the following code will also work for non-trial if your key has an expiration date or number of runs. Try it: Public Function ReadTrialState() Dim XLSPadlock As Object On Error GoTo Err Set XLSPadlock = Application.COMAddIns("GXLSForm.GXLSFormula").Object ReadTrialState = XLSPadlock.PLEvalVar("TrialState") Exit Function Err: ReadTrialState = "" End Function