I stumbled onto an article that claim that :
Source: http://www.labnol.org/internet/blogging/language-translation-plugins/7781/(...)the terms of the Google Language API do not permit sites to store translation results in the database for a long time:
You may copy, store, archive, republish or create a database of results returned from the service, in whole or in part, directly or indirectly, except that you may store results in a temporary cache for a period not to exceed Fifteen (15) days solely for the purpose of using those results to carry out a specific user-requested action;
I followed the link provided in the site but I didn't find any condition with that text.
Here is what i found that is the nearest to the text above:
transmit any viruses, worms, defects, Trojan horses, or any items of a destructive nature
Thanks for your comments.
PS: Sorry for my bad english