Food safety organisations recommend storing butter in the refrigerator to increase its shelf life and prevent food-borne illness. While it is usually best to keep the butter in its original wrapper to protect it from light and air, you can remove the butter from its packaging and mix it with a liquid fat to make it creamy and soft. Different oils affect the taste of the butter so choose an oil you like the taste of on its own or experiment with adding different oils to the butter to compare the taste. Whatever oil you use, it may start to solidify after a little while in the refrigerator, but the butter/oil mixture should still maintain a spreadable consistency.
Remove the butter stick from the refrigerator and leave it on the counter until it softens -- usually within 30 minutes.
Scrape the softened butter from the paper into a bowl.
Pour 1/2 cup of a cooking oil such as canola or olive oil into the bowl.
Blend the mixture together with a hand blender until it's thoroughly combined and creamy.
Place the mixture in the refrigerator in an airtight container. It remains soft and spreadable, even after sitting in the fridge for hours or even days. Make only enough soft butter at a time to last about two weeks.