I have 2 SXT lite 5 with lvl4 licence but after upgrade to ros 6 and update lincense key, the router lost lvl 4 and now have lvl3. I want my lvl 4 back. It’s not nice what you are doing.
I’ve send an mail to support also. 
Did you attach the supout.rif to the email?
SXT Lite has L3 keys. Why do you think you had L4?
You forgot it?
http://forum.mikrotik.com/t/sxt-lite/62648/1
OK, we need to see those files.
this is the other one
As it was discussed before - some (very few) devices came with a “bonus” L4 license, but not all. Don’t expect all SXT lite devices to have L4 license, default is L3.
License can’t be downgraded by accident, router can’t generate keys by itself. If you see L3, it means you always had L3.
Normis, How to recognize bonus devices?
Look in the “system license” menu.
Ok, but is it possible to recognize bonus device in the shop?