For that kind of thing, I have a "config" table in the database to store the value. Then this can be read and updated each time the package runs. You could also use a text file, but that is not as secure.
Edit:
I achieve this by invoking a SQL Task at the end of the Package that calls a stored procedure. This SP accepts a bit parameter indicating success (1) or failure (0). The SP uses GetDate() to record the time that the Proc ran (which is when the Package finishes).