I am created an ad site where people can upload an ad to stay for two weeks
before being automatically deleted. I first thought of using auto increment to
create the product Id, but I realize that this would cause problems later when
their record is deleted.

I need advise on the best way to create an appropriate product ID in a
scenario where the id field will constantly change (updated). When a record it
deleted it ID could be used again.

Thanks

I don't see what problems it would create. But, if you want to use something else, how about making the field char(35) and create uuids to get the values.