For example, in month 1, you lock 2000 $LZ to join LZ Platinum Pool for 6 months. The next month (month 2), your friend also decides to join LZ Platinum Pool, so he has to lock 2500 $LZ because the locked requirement increases for this month. At the end of month 6, as your locked amount is soon to be released, you choose to join LZ Platinum Pool for another 6 months to have access to more private/seed sales. This time you need to lock 2000 + 500*6 = 5000 $LZ.