Since a registration's expiration time is 90 Days.
So I plan to check first for every concern devices/registration before sending any notification. Because I don't want to keep anything on server.
However, I'm not sure if it's good idea to do Is it slow to do for lots devices ?
Also, I can not find a way to set Expiration time of any registration So I've never seen result when sending to expired device ?
Can anyone suggest ?