Is microneedling a lifetime process?

I take minoxidil, finasteride, and tretinoin and want to add microneedling.  Will I have to continue miconeedling if is works on my head?

If microneedling produces hair, it is likely that microneedling will have to be continued on some maintenance schedule for your entire life. So, for example, if you start doing it once a week for 6 months and get the growth you wanted, you could step back to once a month, which might suffice.  I certainly will not guarantee this.