I tried the trial version (though it was limited), liked it, bought it, and then tried to use it, but...
Even though the app store showed I had purchased it, every time I tried to use it, it loaded as a trial version. I wasted an hour trying to figure out how to get it to work before finally contacting Microsoft for a refund. In the end, this app cost me way more time than it saved me. Look elsewhere for inserting dates in Excel.
UPDATE: Microsoft won't give me a refund now. I have to contact them in a few days after the charge posts. Seriously, Microsoft has a lot to learn from Google. If I want a refund on an app, I take care of it within the store. I don't have to write tech support...twice.
UPDATE 2: In five minutes, using Google Spreadsheets, I created a file with a date picker...hassle free...and free.