Requiring illegal rental permit be renewed for offer

[Eugenia K.]

I was wondering if anyone had experience with writing or receiving offers that required a property's rental property registration be renewed. If so, how was that constructed? 

For context, I'm in negotiations on a property that has been running a rental for over a decade without the proper ADU permits. The rental is registered with the city, though the registration expires in a couple of months. Therefore, it would expire post-close if I do nothing. Rather than my potentially running into issues in renewing it right after purchase, I'd like to add a requirement that the rental needs to be renewed by the seller prior to close, so I have adequate time to legalize the unit.