The API currently allows for per application API keys, limiting the APIs use in terms of third-party services that would like to make use of it's real-time data. Taking the standard approach of many APIs and implementing per user access tokens would allow for applications of the Companies House API beyond personal projects and research groups with little to no further alteration to the API.
If possible, please may a representative let me know if such a feature is likely to be added in the future or is currently under development, thanks.
Note: I understand that the rate limit is there for a reason and I think it is generous for any individual user. Furthermore, this service being designed for real time retrieval of data as it is required and not for the collection of large data sets warrants rate limiting. However, implementing per user access tokens would not undermine these constraints and would go to further the APIs goal of ensuring that all customers get equal access to the data while making it available to more diverse applications.