the thing with permits is you just don;t really want them to expire, as some states can make you re take tests or qualify or??
and if things ever go south, you MIGHT be grandfathered in if you keep your permit active!
as for the 45 day deal, not sure what state your in, but in PA< for an example they will send you a notice(some times NOT always, I have had my permit in PA several decades now, and only got one notice, happened to be last dec! and by the time I got it, I had already renewed my permit?? LOL), as you can renew sooner than waiting for exact date to happen??))
but they have been trying to send notices out a few weeks before things expire, to allow you time to make time to go in and renew things. the bigger issue the past two yrs however has been the covid issues, and as such they changed things, wanting you to come in sooner to allow them more time to process things and be able to get you back in before your permit expires
as most sheriff offices the past few yrs have been over run with new permit applications and then the covid rules on being allowed in side there offices has effected things!
under normal conditions and times, All one had to do was go to a sheriff's office the county you RESIDE in, and have them do a new check and picture! and this was done while you waited, unless they were extremely busy or some other ODD event effecting them from being able to process things while you waited, and then you had to come back to try again!
NOW or since covid, they want you to fill out NEW/RENEW applications, hand them in, and when ever they have time they get to them, then they send you a letter or call you to select a time to come in and get your new /permit!!
but again, this is just the past few yrs due to covid, pre covid, it was just go in get a new background check, pass that and your were issued your new permit after a photo was taken for it, that is!
so many states have changed rules due to covid, in time I see things going back to the normal process!