There being no SeaMonkey version, I downloaded the Firefox version (1.1.3) of the extension, converted it via the Extension Converter for SeaMonkey at , and installed the converted result. All conversion options were selected. In the installed extension, I set the "Expire visits older than these days" to 30, which had been my setting before the capability was removed from Toolkit/Places.

At 2/8/16 9:45 AM Pacific time, my history still contains entries from more than 32 days earlier.