I wonder if this calendar will still be being used in 10 years? - feels good just to think about it
Well, as you will probably have seen whilst hacking the code, there is no provision for such a feature. Remember, as I mentioned before, this script was really meant as a starting point for developers to use and adapt to their needs as you are doing so successfully.
I would have thought that the best option would be, as you have suggested, that the administrator had an option to delete old bookings as and when they thought necesary so as not to delete data "without permission" .
It might depend of course on how much extra data you added to the table - It would be fairly easy to add actual client data to each date or individual date prices and maybe it would be better to "never" delete this information.
Obviously actually deleting the data is not hard at all so I would have thought that the final method would be best defined by the "client" (ie the person you are developing the calendar for) so as to avoid any confusion.
Chris