This feature is currently not offered in Blogdrive for both the free and paid accounts, but there is a way to add a monthly archive without tearing your hair out.

If you click the url shown in the Calendar, you'll note that it appears in this format:

http://techbot.blogdrive.com/archive/cm-02_cy-2007_m-02_d-28_y-2007_o-0.html
If you dissect it, you'll see that the archive url first labels the month and year, and then specifies the duration to display latest and earliest dates to display:

02_d-31_y-2007_o-0
02 is the month, 31 is the latest date, 2007 the year, and 0 the earliest.

Specify the last day of the month, be it 28, 30, or 31. Note the code only works when the month is actually up otherwise it'll send you to some http page.

So build a series of links:

<a href=http://techbot.blogdrive.com/archive/cm-02_cy-2007_m-02_d-28_y-2007_o-0.html>February 2007</a><br>
<a href=http://techbot.blogdrive.com/archive/cm-01_cy-2007_m-01_d-31_y-2007_o-0.html>January 2007</a></a>
<a href=http://techbot.blogdrive.com/archive/cm-12_cy-2006_m-12_d-31_y-2006_o-0.html>December 2006</a>
and paste them in side.html. Voila! :) You have your archive.

Technorati: blogdrive, monthly archive, code, fix