I was thinking on buying Sono Hanabira on Mangagamer (Potential NSFW Warning for adds) to support English localization of Shoujo Ai/Yuri titles, but much to my disappointment it's digital only so i would only be buying a Steam Key.
Since i do not have Steam installed but i do have an account (uninstalled Steam because it was more or less useless to me) i was wondering how long a Steam Key is valid for, if it ever expires.