Free classifieds | Duration Custom Field

Hello! the classifieds on my BP installation will be free so I didn´t set credits or payment functionality, but there is a "Duration" custom field that has by default the options of 1 week, 2 week, 3 week, etc.

I want to edit the duration field to 30 days, 60 days, and 90 days. How do I do this for the plugin to recognize the new time limits? Where in the settings or the configuration do I tell the plugin that these are the 3 options and time limits?

How do you set the time limits on this plugin? are set 1,2,3,4 week options "hard coded" and they cannot be changed?

Thx, Donald.