WASHINGTON — The same week that Alex Haro and Chris Hulls raised $50 million for their mobile app, Life360, the business partners got a letter. It said they had three days to pay licensing fees to a company they had never heard of because their app violated its patented technology. Haro and Hulls traced the company, Advanced Ground Information Systems, to a coastal home in Jupiter, Fla., with a phone number that initially went to an anonymous voice mail. They couldn’t find any employees on LinkedIn. To …