LME in a sealed can has a 2-year shelf life. I would want it as fresh as possible.
The LME from the LHBS was from a bulk barrel. My oldest is Amber; that is from January 2021. A second Hawaiian Punch bottle is Pale Ale from October 2022. I also have several cans of mr. beer kit syrups from July 2022 up to just a few weeks ago. The Amber and Pale Ale are in my icebox; the mr. beer syrups are at room temperature.
I scraped a little LME from the inside of a container, mixed it with some filtered water and placed it in my fridge several weeks ago. I looked at it today and I saw that several spots of greenish-blackish mold had formed along the upper surface of the liquid. I was going to pour that stuff into my near-gallon bottle of Amber LME, but decided against it. I had some remaining from when I poured the stuff from a very-nearly full, cylindrical container into a Hawaiian Punch bottle. That remainder I put into a one-liter bottle with a cup or two of water and then into the freezer with it. I'm interested to see if the sugar in the LME will fall out and I'll have sugar crystals along with a sticky malt mess when I go to warm it for Brew Day. The idea is to use as much of the malt as I can because I have to pay for it, y'know. No reason to throw it away if it can be saved, once diluted with water. If nothing else, I may learn something about LME that I do not now know.
i promise you, no one here is trying to talk down to you by giving advice that runs counter to some ideas you may have had or have. but, ive seen a bunch of your posts on how you want to brew.
afai can tell you have some experience with brewing, but are still starting out.
i feel like ive learned best by doing the hypothesize, test, record methods and results, then think about what i would change in the next brew. obviously some beer gets brewed along the way, but going for a single well, experiment and focusing on it and trying to assess what worked and what didnt and maybe why, then improving it is a common sense way to work towards becoming a good brewer.
LME can definitely work, but plan for a single brew and eliminate the hard-to-qualify variables of uncertain LME quality and age. Just buy some fresh extract and see how that works. my first beers were sort of extract/concentrate-wort kits you added water to. i thought they turned out really well at the time tbh and it definitely motivated me to see how i could improve. the next step after that was adding steeping grains to the kit.