score:3
I assume, that you have bought that ticket and it is stored on personalized card. From ZTM's site (in English):
90-DAY TICKETS
entitles to unlimited number of journeys from its [validation] until 23:59 of the ninetieth day of its validity
Now, the word "validation" is missing in original text, but it is mentioned in Polish version of the site.
That would mean, that you have to validate it only once, the first time you'd want to use it. Then, you don't have to validate on subsequent bus/tram rides. In subway you still need to use the card to enter a platform.