Smoking is permitted only on the balcony. No more than 4 guests per night. Photocopies of the passports of all guests will be requested when the apartment keys are transfered.
I'm a Canadian of Armenian descent who has lived in Yerevan for several years. If you're new to Armenia, I can tell you where the non-smoking venues are, where you can find good vegetarian food, and where to get your bike fixed :)