If you have Gold status

Travelling Economy Class : No Guest Permitted
Otherwise : 1 guest

The person does not have to be in the same booking as you ; if you are booked in business class and the other person on the flight has a separate booking in economy class, then you can take that person in as guest. At Dubai, if travelling in 1st class , you can take a guest who is travelling in either economy or business into the 1st class lounge