I typically have to buy a new tube every time I need to use FIPG. Just because the last time I opened one, this previously opened tube has expired. I will on occasion use an expired tube if it's a non-critical application that isn't a PITA to get too. It's on my personal vehicle so I'm not going to lose sleep in doing this.
In a previous life, I worked around a lot of materials that had expiration dates that were strictly adhered to; epoxies, thread lockers, spray coatings and lubricants, etc. There was a regular audit and "purge" of these materials. After the collection, I used to pick out the thread lockers/primers, Dow-Corning greases and o-rings for use at home.
I always found it asinine that the day before the expiration date the material was good, but not good the day after.