Yeah as I've checked the internet each countries has different policy towards their lottery winning claiming some
has 3 months , some are 6 months while others even give them 1 year, which means we must check the rules or ask the teller
first before putting your number combination(this is about physical casino)

But about online casinos? they also have time frame in their TOS but one thing is for sure that each lottery has
 expiration either Online casino or physical one because the casino will not let that amount just seat waiting for claimant all their time.

also I was wondering why would a Lotto winner take long time before claiming? this is the biggest winning in
 gambling world and as you have betted  surely you understand that faith and will not let the winning wait long to take.