Amazon has announced the following changes for Fulfillment by Amazon (FBA)
Long term Storage Fees: Starting February 15, 2019, long-term storage fees will be eliminated for items that have been in a fulfillment center for 181 to 365 days. Long-term storage fees still apply for items that have been in a fulfillment center for more than 365 days. and they have also reduced its fees to $0.50 per unit to $0.15 per unit.
Fulfillment fee changes, see US FBA fulfillment fee changes(Login required)