This topic is probably relevant for only a few people, since it involves a particular combination of software and is rather technical.
I use Chrome as my web browser and used EditThisCookie as an extension. This allows you to do various things to cookies. I used it to edit the cookies the site produces. One of the things I did was set the expiration date to 2019, so I wouldn’t have to log in for some time, so I thought. The site clearly had a different opinion and I had to log in any way after some time. And this went wrong: I couldn’t log in anymore. The only remedy was to reinstall Chrome (removing the extension didn’t help).
So if you use this extension: be careful what you do.
By the way, the reason I used this extension was that CCleaner, which I use to regularly clean up my computer didn’t recognize the cookies the site produces. CCleaner allows you to indicate which cookies not to delete, but that didn’t work in this case. I now use the commercial/professional version of CCleaner and this does recognize the cookies. So I can recommend this to you.