Unplugging wont effect the settings. The plugs themselves use less than 1w. It's really up to you weather to leave them physically plugged in or not. The real question is why aren't you using them? If they are for seasonal type devices you could always repurpose them in the 'off season'. For example I have plugs I use for fans in the summer, in the winter I use them for holiday lights. If you do want to unplug them but have timers, senses linked to them. You may want to label them using a cheap label maker or marker which will make it much easier to figure out which one is which when reinstalling.