It's a card that authorised me to use the DECsystem-10 mainframe at Essex University. We used to get one of these every year, or more than one in some cases — I have another for [2301,2301], which was my academic account at the time ([2600,2776] was my Computer Society account).
Yes, the mainframe was so weak and puny that access to it was managed using a card-based system so as not to overload it with extra work. To be fair, it was approaching the end of its life and we did have personal computers back then; nevertheless, it still feels weird that this was only 25 years ago (although not so weird as the feeling I get from feeling that 25 years ago merits an "only").