Hi, @Elaine119. Type Lithium into the search box in this forum and you will come up with multiple explanations:
Lithium and Schoolkeep (not Schoolkeeper - did yours say Schoolkeep or Schoolkeeper?) are reputable (i.e., google-able) and harmless.
Lithium and Schoolkeep gather information about us. You can delete them but they pop up again when you next sign in.
Lithium and Schoolkeep were temporary in 2015 during a transition and would go away in a few weeks. Nothing to worry our pretty little heads over.
The presence of Lithium and Schoolkeep on your device needs to be reported to the Airbnb developers.
Your choice, but it seems they are used by Airbnb, and here to stay. You might contact Airbnb if you are worried. That was the advice of an administrator on one of the threads from a few years ago.