"John T" wrote

In short, FAA pilot certificates do not have an expiration date (so
there's no need to "extend" the certificate). However, they are only
valid in conjunction with a current medical certificate which do have
expiration dates.

Beyond that, you only have maintain currency per 14 CFR 61.57:
\

Don't forget the need for the Biennial Flight Review. Gotta have that, too.
--
Jim in NC