While I am sure individual departments (even state departments) may have continuing eval/education requirements, so far as I am aware, no state in the US requires a state-wide licenses, with state mandated requirements for all licensed Police Officers in the state to maintain their license (unlike Doctors, Nurses, Lawyers, Accountants or even Real Estate Agents).

I would be happy to be proven wrong if someone can point me to a link that specifies otherwise though.

Edit: seems the OP decided to delete their post that a state could decertify a LEO, and that minimum continuing requirements already existed, instead of providing some links supporting their claim.

I decided to look a bit and found this: https://www.ncsl.org/research/civil-and-criminal-justice/decertification.aspx it looks like in a small minority of states there is some possibility of being able to decertify a LEO, but I have not gone through and looked at how involved (or lasting) that process is.