Firefox sign me out from google every few days
I have a problem with Firefox and google.com (plus all google services like gmail, gdrive, youtube etc)
When I log in to google account and work there for a few days everything is fine. I don't even close the Firefox. But suddenly every 3-7 days I see that I've log out from google account.
How can I stay logged in to google constantly?
p.s. I've tried to clear the cache, delete cookies, even reinstalled firefox. It didn't help. Another browser works fine and don't log me out.