Comment by w3ll_w3ll_w3ll

Let's encrypt decided for 3 month to force users to automate and avoid the burden of too much user support. They are a no-profit after all.

I believe commercial CA are offering free certificates milted to 3 months for the same reasons, and for the up-selling opportunities.

I think also cloud providers offer free 1 year TLS certificates, but of course you are also using their other services.