INT 2F - License Service API - UPDATE
        AX = 7003h
        CX = license server index (0000h to 001Fh)
        DS:DX -> SLSUPDATE structure
        ES:BX = provider specific handle for the license context
Return: AL = status
            00h not installed
            FFh installed
SeeAlso: AX=7005h

Format of SLSUPDATE structure:
Offset  Size    Description
 00h    DWORD   (return) status code
 04h    DWORD   (call) handle identifying license context
 08h    DWORD   (call) total units consumed
 0Ch    DWORD   additional units required
 10h    DWORD   address of comment string
 14h    DWORD   address of SLSCHALLENGE structure (see AX=7001h)