In version 7.5.8, the dev erroneously set the "hardcoded maximum cookie expiration time" to 7 days.
In version 7.5.9, the "hardcoded maximum cookie expiration time" was correctly reverted back to 365 days (1 year).
A discussion (and a manual fix) on this 7.5.8 issue was posted at -
https://www.ubbcentral.com/forums/ubbthreads.php/topics/254650#Post254650Further discussion on this 7.5.8 bug can be found at -
https://www.ubbcentral.com/forums/ubbthreads.php/topics/256642#Post256642---
This and several other bugs have been resolved in 7.5.9
The changelog for 7.5.9 can be found at -
https://www.ubbcentral.com/forums/ubbthreads.php/topics/256313#Post256313