
Certified GKH Gardening Expert
I would not store it in bags at all! The longer it sits in bag the more opportunity for infection there is.
In fact, a good way to re-use spent soil is to compost it! Just add it to your compost pile, or composter. This way, it has proper aeration and can be turned as it needs to be.
Re-using soil in this manner, becoming part of your compost, will leave you with a better product after composting.
Here are some articles that will help you to make your old soil usable again:
https://www.gardeningknowhow.com/composting/basics/ultimate-beginners-guide-composting.htm
https://www.gardeningknowhow.com/special/organic/the-importance-of-soil-for-an-organic-garden.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/improving-garden-soil.htm