Hi enanos, hopefully I understand your questions correctly but looks like you are asking if fpp's expire maybe?
If that's correct not they don't expire.
Not sure what else the question could be unless you're wondering if you could find out how many fpp's you earned in a certain month in the past? In this case you could request an audit i think its called through the ps client and it has a field you could tally up the fpp's for the month.
Hope this helps, If I did not understand the question please try and post it again (perhaps run it through a translater from your own language if this is not what you had done previously).