Instead of trying to make a quick buck on this thread like everybody else I'm going to provide you with a answer to your question.
Tokens for any app, IG, FB, etc. are useful for developers to get access to a apps api. Usually an API token is a unique identifier of an application requesting access to your service aka bot for us blackhatters. Your service would generate an API token for the application to use when requesting your service. You can then match the token they provide to the one you store in order to authenticate.
