my old GMDSS & Marine Radio Operators Permit had expiration dates (2012) but I had heard time and time again that they never expire. after hearing some scuttlebutt on my ship (The Caesar) I did the following:
with my current (and non expired) certs in front of me, I went to the FCC site (https://fjallfoss.fcc.gov/coresWeb/publicHome.do) and followed the links to update my information. I updated my address and email address, then submitted the changes online; the whole process, which costs nothing, took maybe 5 minutes max. I received my new FCC certs which have NO expiration date within 7 days.
damn, I was impressed with the FCC.