enable specific categories for vendor

I am setting WCFM marketplace plugin on my website. I have 10 categories on my website but i want to enable vendor’s to publish their products in only one category from all. how to achieve this?
when i choose specific category in marketplace settings=>product type categories and save. It save the settings and on refreshing page again come to default.
can i customize plugin if this feature is not available for free members? I know a bit of coding but need direction on which file should i see to edit in backend?

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