Microsoft 365 Business Premium
The top small-business Microsoft 365 plan, bundling Office apps with device management and a real security stack, capped at 300 seats.
It includes Entra ID P1, Intune device management, Defender for Office 365 Plan 1, and Defender for Business, which makes it substantially more capable than Business Standard for anyone who cares about security.
The 300-seat cap applies across the whole Microsoft 365 Business family combined. Past that you cannot buy another Business licence, though you can keep the 300 you have and license additional users on E3 or E5 in the same tenant.
Where this comes up
Microsoft 365 Business Premium sits inside our microsoft 365 and cloud work. If you are trying to work out what this means for your own environment rather than in the abstract, that is the page worth reading next, and a short call will get you a straight answer faster than either.