Can you help me understand what the correct journal entries on December 31, 2018 should be and why?

Lil Tykes offers 1-year, 2-year, or 3-year subscriptions to a number of magazines. Payment for subscriptions are collected in advance and credited to the magazine subscriptions collected. The balance of this account was $1 250,000 on December 31, 2018. On December 31, 2018, subscriptions that are outstanding and expire are as follows. Expire in 2019 $350,000 Expire in 2020 300,000 Expire in 2021 450,000