I'm building a website with some friends that does social media analytics. As part of this website, there's several places on our site where a website user is prompted to enter some text with the phrase "Enter your [SERVICE] account name", where [SERVICE] is the name of a social media site (Facebook, Instagram, etc.). 

Are we allowed to do this? Does it vary by social media service and the company's specific rules surrounding the use of its IP? I've seen some other social media analytics sites get shut down for this kind of violation (using a social media service name while not being affiliated with the social media service), even if it may have been accidental (i.e. they weren't trying to claim the trademark, just reference it when describing their product). I think this might fall under the category of "nominative use", but I'm not at all sure.