Let's Encrypt launches with 90-day certificates (2015)
Let's Encrypt launched its public beta in December 2015, issuing free certificates valid for 90 days. Commercial certificates at the time commonly lasted three years.
The 90-day lifetime became the norm for automated certificate management.
It proved short lifetimes with automated renewal could work at scale, setting the stage for further cuts.
The 64-day change is the first reduction to that 90-day default, applying the same logic: shorter lifetimes limit the damage of key compromise.
