How to ensure if all the liens/permits on fourplex are closed

[Anna Sam]

Hi

I am in the process of purchasing a fourplex and want to find out the best way to ensure that the contractors who worked on it have been paid and all permits are closed out.

Seller is fixing property and I am buying it in rent ready condition.

How do we stop any contractor from filing a lien after I close on the property?

Please share your thoughts. Thank you