A noncreature permanent that becomes a creature can attack, and its {T} abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn't matter how long the permanent has been a creature. Notably, if you turn Mishra's Factory into a creature on the turn it entered the battlefield, you won't be able to then activate its first or last abilities.

After it becomes a creature, Mishra's Factory will still have all its abilities.