How can I translate Different languages in to English in R?

I want to do sentiment analysis on customer reviews but they are in different laguages some are in German, some are in spanish, and many others. I tried to use translateR package but I didn't get desire output. I think I didn't generate my google API key properly Can anyone please tell me how can I convert multiple language in to English and How can I generate Google translator API without Billing? Please give me some suggestion.