CPLEX is free for academic use...i.e. teaching, not for research.
Universities can use it although strictly speaking if being used for research instead of teaching this is likely a contravention of the license. Any not-for profit research institute that is not a teaching institute will have to pay for the license.
It may be better to remove a dependency on a commercial piece of software. GLPK provides similar functionality to CPLEX and has python bindings but I appreciate that modifying the code to use this instead of CPLEX is a big ask.
CPLEX is free for academic use...i.e. teaching, not for research. Universities can use it although strictly speaking if being used for research instead of teaching this is likely a contravention of the license. Any not-for profit research institute that is not a teaching institute will have to pay for the license. It may be better to remove a dependency on a commercial piece of software. GLPK provides similar functionality to CPLEX and has python bindings but I appreciate that modifying the code to use this instead of CPLEX is a big ask.