mine comes from the supplier with electrical tape wrapped around the lid and bottle , it lasts way longer that way IMO
That's mostly for shipping. The problem of this stuff drying up or setting, seems to come, as mk162 noted from air that enters the bottle as it gets emptier.
In an ideal world, the original container would be like the "accordion" bottles we used for photo chemicals. that could be compressed to eliminate the air pocket.
Otherwise, I do find that storing upside down does increase the life of the goo inside.
Plastic wood and other products that can easily dry out come this way.