You should cite the Gurobi software if you are using it in your publication to obtain the solution of a specific model. Another reason would be the publication of a source code containing calls to the Gurobi API.
For citation of the Gurobi software, we suggest the following BibTeX citation:
@misc{gurobi, author = "Gurobi Optimization, LLC", title = "Gurobi Optimizer Reference Manual", year = 2020, url = "http://www.gurobi.com" }