Can active FX laser cause permanent swelling? I had procedure done a month ago and still have some swelling on upper cheekbones

While it is difficult to determine whether your swelling is normal without seeing you in person, I can tell you that it is not unusual to have some residual swelling in the midface at this point. I recommend continuing to sleep with your head elevated to manage the swelling. You can also place warm compresses on the area. I would expect you to begin seeing improvement in this swelling in the next few weeks. However, you can always schedule a follow-up with your doctor, who can evaluate you in person and put your concerns to rest. 

This is a good question! However, it is difficult to give you a definitive answer without an in person visit or a photo.  In our office's experience we tell our patients that they are red and crusty for a 1-2 week and then redness and puffy for up to 2 weeks.  We educate the patients that the redness may last up to 6 months post treatment. I would recommend that you see a board certified dermatologist or plastic surgeon with cosmetic training so to open further dialogue with the treating physician.

You swelling is not permanent and will resolve.  Everybody reacts slightly different to device treatments.  The majority of swelling should resolve by 2 weeks but this does not mean that you will have residual swelling up until the 4th week.