Did you get your answer? If not here you go: PokerStars
tickets can be used on any Sunday and they are valid for 1/one tournament which is the "Weekly Round 2" which consists of a $1k Prize Pool and usually has up to 3,000 entrants.
Tickets can be used any Sunday
But, when you win your ticket you are pre-registered already for the tournament. You need to click on Requests: Registered in Tournaments
It should take you to the Tournament lobby and you can Register/Unregister there.
I hope that helped you out PM me if you still want help