Attempting to lock dates into a cell after they are populated

A macro similar to this one would do it.

Sub Macro1()
    Range("C1").Select
    Selection.Copy
    Range("B2").Select
    Selection.PasteSpecial Paste:=xlPasteValues
End Sub

This assumes your formula listed is in C1 and you want the permanent date in cell B2. It would only update when you invoke the macro.