Do I need to register my Russian visa?
Yes, if you intend to stay longer than 7 working days in Russia.
All foreign citizens entering Russia must register their visas upon arrival in cases when they are staying for more than 7 working days. An unregistered visa may cause problems and fines.
Your hotel/host/sponsor/inviting company (Russian citizens or foreigners having a permanent residence in Russia) need to assist you in registering your Russian visa.
If you change cities, you have to register in every city where you are staying for more than 7 working days.