The Xpress method for optimization requires a license for the Xpress Optimizer commercial solver.
Use the community license
A dated community license is included with the Mathematica installation. After it expires, you may request a current community license from FICO. The community license is subject to restrictions on problem size.
Get a free trial or academic license
Request a free trial or academic license from FICO.
Purchase a license
Alternatively, purchase a commercial license from FICO.
Verify the license
Evaluate an example with the Xpress method in the Wolfram Language to verify the license: