I found this special lamp designed for photo studios.
Nobody knew to tell me from what year was made,i only found that 'L7' marked on the neck means something,according to a table found on a website the  L would be November but the 7 i don't know if means 1967 or 1987.
What do you think? Also i found that these lamps have short life,something about 3-6 hours,is that true?
Thanks in advance for your help!

Those lamps are indeed not meant to last more than a few hours due to the filament being over driven to up the color temperature and brightness.

It‘s definitly 1967 regarding on the card board box with the very old design.