If the business use was started as a legal use and zoning regulations have since changed, the business is still permitted to operate in its current fashion. The use would be considered a legal nonconforming use. However there are limitations relative to the future such as expansion, rebuilding or otherwise modification of the use.
If you are proposing to locate a business where the use is not supported by the Zoning Ordinance, you may want to consider rezoning the property to a district that accommodates that particular use. Consult the Land Use Plan to verify if the plan supports the proposed rezoning.
The Land Use Plan designates areas as residential, commercial, industrial, or a mix of those uses for all portions of the city and Urban Growth Boundary. You will need to verify what the Land Use Plan calls for in that location. It is possible that the location of your business could be designated for residential use currently or in the future and not suitable for rezoning to a commercial use.