According to the Lobbying Disclosure Reports[0], if you add up outside council for Facebook, they're paying about $156,000 PER MONTH on lobbyists. You'll want to look at 2017 Q4 reports, as Q1 is not yet due and they don't file until it's absolutely due.
At less than $2,000,000/year, that's pocket change to FB ($30B in annual profit). Facebook probably spends more money on flavored seltzer water than that.
[0]. http://disclosures.house.gov/ld/ldsearch.aspx