Help converting a .sldprt to STEP

Hello to all! I have a problem with a model, that I created last year, when I had Solidworks school licence. I finished school before summer, so my licence sadly went away with that. I now need to convert the model to STEP format, to be able to work with it. I tried to search for online converters, but as I understand - it's a closed source format, so I am not able to convert it this way. The model is not very complicated, but it has exact measurements, which I need. It was made in SW 21. All the people I know have older versions. My question is, if anybody knows some way to do this? Thank you very much!