Before it's opened, keep it in a dark cool place and with the cork lower than the bottom of the bottle. It will be good for years. After opening, reseal it well and keep it in the fridge. It will be good for up to a week.
If refrigerated 2-4 weeks depending on how many times the bottle is opened. With each exposure to air 21 % oxygen this will increase oxidation. Not good with a wine withe the sugar content of plum wine. dr Dr.Nurse