See Working with context : Node-RED and A guide to understanding 'Persistent Context'
Are you using HA? If so then you will have trouble getting help here with those nodes and very few here use HA. In fact many think that it just complicates things and prefer to use node-red for everything.
If you didn't know about persistent context then presumably you haven't watched this playlist: Node-RED Essentials. The videos are done by the developers of node-red. They're nice & short and to the point. You will understand a whole lot more in about 1 hour. A small investment for a lot of gain.
