It is not confessing anything, because it’s not a valid confession, and because the statute of limitation may have already passed. I’m not even sure what the statute of limitation is on having used drugs or having possessed drugs. If using drugs is a meaningless crime, having used drugs a year or more ago is an even more meaningless crime.
Memoirists talk about past drug use all the time. The last President of the US did as well. None of them get locked up for writing memoirs.
