i hope i am reading your question correctly.
if you buy a bonus pass that has free days on it, then it would expire 4 days after you first use it. if you use only 3 days of that bonus pass and leave the orlando area, come back 2 weeks later, you would not have 2 days available on that pass.
if you bought the special bonus days that did not have free days on it, those passes would be non expiring.
i bought that 3 years ago and did not use all my days on it. the cost for that pass was under a special promo but not as cheap as the $99 one listed now.
my one day ticket is still valid. i had it checked out at guest services before i left last october on my last trip there.
from what i understand, if you buy the 2 day 2 park bonus with 3 extra days, and never use that pass, it will be valid pass the dec date.
i suggest you call guest services at universal and read the numbers off the back of the pass to any employee there to get confirmation of what i said.
if you are told by an employee, then you have no worries on the validity of the pass that was never used.
some people buy the special passes that universal has advertised on line with the use of your master card. you buy 4 passes that are 2 day 2 park tickets and you get a 5th pass FREE.
my friend and i did this before. she needed 4 passes, i needed i pass.
she ordered them on line and had requested them to be mailed to her for an additional charge. i gave her a portion of the cost and she gave me one of the 2 day 2 park passes.
i used it a year later after she bought them and used her set.
it was a valid pass and i had no issues with it.