As noted above, the sun never sets on T3...
In DXB T3 there is the Marhaba lounge, to which you can buy into (or free with some credit cards, but it's a very specific list, or Priority Pass). Admission is $48/person otherwise. It's OK - free wifi, light bites, drinks. Not sure if it's worth $48 given the other options in DXB.
https://www.marhabaservices.com/source/lounge.aspx