Well, there are two bugs in this product:
Bug #1
There aren't notifications for email based subscriptions. I mean, members only get notifications of threads subscriptions made with the option "without email notification". If someone has a thread subscribed with instant/daily/weekly email notification then they will not receive notifications in the top right corner but email notifications will be dispatched to the member's inbox as usual.
Bug #2 (strange)
After marking all forums read the subscribed threads notification is still present (it's always 1). I remember it was working fine but now it isn't. That's why I'm marking this bug as strange.
I'm talking about the NOMEMCACHED version running in a vB 3.8.5 forum. The programmer already said that that version is provided as-is so we can't expect any further updates