I was inspired by Sal Uryasev, who wrote the first unofficial Google Trends API and made it public. That's my fork of his repo: https://github.com/mac-r/unofficial-google-trends-api. The problem is that his code doesn't work anymore. I didn't like the idea of creating a new session as well.
My script (https://github.com/mac-r/trendo) allows to get daily data per specified month without any authorization.