Is the same true of a Senior RC discount?
Or, to put it another way - when a new SCRC is bought, does the discount have to be re-applied?
For the person adding the discount, you just type in an expiry date. If you type in a date three years away, the discount will stay for three years. If you type in a date one year away, it will expire in one year! Perhaps the person who added yours did it wrong...!
There was a (Recently corrected) issue with adding three year expiry dates for some railcard types, although staff should have pointed this out.