But my last Medical was maybe 15 years ago and expired.
So looking into BasicMed notice I was outside of the 10-year window. Which guess means I have to get a new class 3 Medical.
There is no "10-year window" in the regulation. The regulatory criterion is whether you held a valid medical after July 14, 2006. So "maybe 15 years ago" might be good enough depending on the date you got that medical and your age on that date.
That said, the Basic Med checklist asks about marijuana use within the past 2 years. If you stopped using it more than 2 years ago, and your last medical was still valid after 7/14/06, and your past use didn't constitute "abuse" or "dependence" as defined in the instructions on the Basic Med Form 8700-2, you could go Basic Med right now, but you would have to forego any further use of the substance as long as you want to keep exercising FAA pilot privileges. Otherwise, what Bruce said applies, because the Medical Application Form 8500-8 asks whether you have ever used marijuana, not just the last two years.
In all of this, keep in mind what Wildermind said -- even if your use was legal under state law, it was illegal under Federal law, so when the FAA asks about use of an "illegal substance", marijuana is included even if it was legal by state law where you used it.
Finally, for anyone who is a pilot, or is contemplating becoming a pilot, it's a straightforward choice between two mutually exclusive options - being a pilot, or using marijuana. If you want to be a pilot, keep your distance from marijuana in all its forms, including CBD products (which can produce a positive drug test indistinguishable from THC and drop you in the middle of an FAA mess).
I want to get back into flying (sport light or experimental) and have joined the Rusty Pilot program. But my last Medical was maybe 15 years ago and expired.
So looking into BasicMed notice I was outside of the 10-year window. Which guess means I have to get a new class 3 Medical. As I mentioned above, just wondering how this will affect me going forward.