Season pass tracking

Hi everyone

I’m trying to build something in Logseq to track my squash ‘subscription’. They sell hours on the court in packs 12 at a time. I’ve purchased 24 hours of play and am looking for a way to track how many is left while logging my games with opponents and training hours.
What would be the best way to handle this? At the moment I’ve created a [[Squash]] page where there is a reference to [[Subscription yymmdd]] with all payment details inside and I log every hour I use the subscription in the daily journal in a form of

HH:mm [[Subscription yymmdd]] game with [[John Smith]]

It works for the logging, but counting the remaining hours is getting hard.

Any suggestions?