If you're playing on PC (Windows 10 Bedrock + Java Win/Mac/Linux), then no; Each named player needs a seperate login as your license is tied to your login/Microsoft Account. If the same user tries to connect to the same server, the previous connection will get kicked (Source: Have multiple accounts).
If you're playing on mobile (Android + iOS), then yes; You can install the app on multiple devices having purchased it once by reusing the same Google Account/Apple ID, unless they're both on different platforms, then you'll need a copy per platform. Each person just needs their own individual Xbox Account and device (you can't split screen).
If you're playing on console (Nintendo Switch, PlayStation, Xbox, etc.) then no, you'll need a cartridge/license/account AND console per player, unless playing split-screen.