Usually, the
cookies stored in your browser, that tell the web "this user can pass, without logging in again" has a lifespan which is set by the developer of the web. There should be something like an infinite cookie*, but
1) I'm not sure this web uses it (and it may not be even in my power to meaningfully do something about it - provided we wanted to), it may just be using a very very long-lasting one
2) even immortal cookies can be deleted by the browser** from time to time, albeit rarely (unless the user does it himself)...
*certainly for a PC web browser
**maybe more frequently on a mobile phone
But yes, I think I'm forced to log in from the same web browser and computer like... once a year?