SpectralRadex has been released under a MIT license and therefore you are free to use, modify or copy it in any way you wish. However, if you use SpectralRadex for any research purposes there are several references you should include.
Firstly, RADEX itself was copied essentially in its entirety and forms the basis of all model ouputs. Therefore, one should reference Van der Tak & Black 2007, the original work. Further, one should take care to acknowledge the work of those producing their collisional data. If you used the collisional files built into SpectralRadex, these were all taken from the Lamda Database where you can find the appropriate references for your molecules.
Finally, and particularly if you used the spectral modelling capabilities of SpectralRadex, we’d ask that you reference the paper in which we first described the module Holdship et al. 2021 (in prep). and point your readers in the direction of spectralradex.readthedocs.io