What are the legalities of reselling a service based on the freeagent api


I’m interested in extending freeagents reporting functionality for my agency using the API. I’m ok with how to do this technically but we were also thinking we may be able to sell these extended reports via a website to other agencies that may be interested in the reports. A bit like https://floatapp.com/

Does freeagent have a terms of service on products like this, are there things we arent allowed to do or have to pay for, for example?

Thanks, Jonny