if you get the api key for just the domain:
www.dumbquestion.com
it will work on maps that you place in:
stupidquestion
as well as:
another_stupidquestion
if the api key is for:
stupidquestion
only maps under the supidquestion directory will work. the ones under another_stupidquestion would not work.
for flexibility, you should just use the root domain.