From noncompact to compact: You must apply for licensure by endorsement in the new state of residency. Your individual state license issued by the noncompact state is not affected and will remain active if you maintain licensure and if so provided by the laws of the nonparty state.
It will remain on your credit report for seven years and 180 days after it was first reported late. Although paying the settlement is unlikely to affect your credit score, it will ensure that you are not sued. A judgment against you is an even worse blemish on your credit report than a collection.
Collection accounts (including medical bills that go to collection) can only be reported for 7 years and 180 days from the date you fell behind on the original bill. After that time they must not be reported. As long as the collection agency has accurately reported the date, this will happen automatically. The only way they can affect your credit longer than that is if they sue you and get a judgment against you.