Yes, using and providing virtual office in Serbia is completely legal and there are a number of virtual office rental companies in Serbia.
The legislator recognizes the need to start a business as cheaply as possible and without unnecessary costs and allows the use of a virtual office for the company’s headquarters. A virtual office enables lower costs for many companies, both companies that intend to operate for many years, and companies that are in the process of liquidation and no longer need a physical office.
English 
Русский