Mary, I haven't checked all of the deeds for Alexander Merrifield, however, I did have a look at the tax lists for Hardin Co., KY.
Alexander was listed in Hardin Co. once again in 1845 and 1846. He was listed with no land so he must have either sold it or perhaps gave it to one or more of his sons. I don't know why it wouldn't be recorded in the deed books.
It appears that Alexander was living in the household of his son Samuel Boone Merrifield in 1845 and 1846.