The Prior Price field displays the item's most recent Price before its Base Price was changed on the Last Price Change date.
Prior Price is updated if an item's Base Price is manually changed or changed by other Keystroke functions such as:
Purchase Manager - When the Update Base Price To New Price parameter is enabled.
StoreLink - When Update Inventory is used to update Base Price.
UDPRICE.EXE - When UDPRICE.EXE is used to update prices using Price Tables.
IMPPOR.EXE - When IMPPOR.EXE is used to import Purchase Transactions.
See:
Inventory Database - More Data Screen Fields