If it is an office lease, selling goods may violate the terms of your lease even if you have a business license. Most leases describe the permitted uses for the space. Most office buildings do not want the traffic that a store brings.
Breaching your lease is not "illegal" but is probably grounds for the landlord terminating your lease and collecting damages as well.
Forum posts are not legal advice, are for informational and educational purposes only, and are not a substitute for proper consultation with legal counsel.