While reading the new licensing guide I came across this section:
The Team Members subscription is a named user subscription designed for users who are not tied to a particular function, but who require basic Dynamics 365 functionality. This license entitles the user to light weight access through designated scenarios built into Team Members experience. The Team Members subscription does not provide access to custom applications and is not intended for scenarios beyond those listed in Appendix B.
So, this means that every user who needs access to a custom application also needs a full user license?