It does a fairly decent job remembering my login here on a PC with a stable IP address and internet connection. I think the phone which is subject to network changes or even a PC with a more dynamic address may not work as well so YMMV. I can go months without having to sign in again. I also do not close out the tab for the forum. I do reboot the machine from time to time - this does not force me to re-login. When I reboot, I press Ctrl-Shift-T in Chrome to force all of my old tabs to restore (if this is not done automatically, which sometimes does happen without my pressing anything). The restored yamahasynth.com tab still has my login remembered most every time.
The same setup was once horrible for remembering logins - so I've seen it both ways. It's also possible that something about my network changed to get the more "lucky" experience and that the yamahasynth.com side didn't change. I believe I have changed internet providers - so it may just be that my IP address is more static now where it was changing frequently before. Pure speculation.
What is not speculation - is that it's possible to have a good experience with respect to login retention even though I don't know the whys or hows of it.