As with most answers, it depends. In general, however, you should continue to take finasteride or dutasteride.
For me, I was a norwood 3ish and then had a hair transplant. The "new" hair should not be susceptible to the effects of DHT, however my remaining "native" hair is, in regards to the crown area and the remainder of the frontal third. Should I discontinue meds, I would likely thin in years down the line.