It sure would be great if, instead of a single date, you could enter a range of dates. E.g. 1/1/2014 to 6/1/1024.
Thank you for your feedback, we appreciate it and will consider adding such date formats in the future :-)
For now, as a workaround, you could set a task to this date:
every day starting 1 Jan 2015
and once you complete it for the last time, hold the SHIFT key while checking it off to force it to move to history.
Thanks for the work around idea.