Windows 10 Enterprise E3 is the license required to access Windows 10/11 multi-session but there are some limitations here. This license can only be used if your users are connecting in from Windows Pro endpoint devices. Furthermore, if you are planning on hosting MsOffice desktop apps on your session hosts then your users will also need a license for this with shared computer activation. In this case Microsoft 365 Business Premium is usually the best recommendation here depending on any other requirements you might have.