Ensure extension exists - Mailing list pgsql-general

I want to use the pgcrypto extension with a particular database. Does it exist permanently and survive a server reboot?
Orif not, how do you ensure it runs when the server restarts? 

I ask because in my Docker development environment I have to run it every time I restart the container, and just want
tobe prepared for production in AWS Aurora. 

Thanks,
Geoff