What was the name of the world's first adhesive postage stamp used in a postal system?

The very early print worth over $340K. could use few of them :)

Cookie Bean the adhesive is activated when it is wetted by licking.

Cookie Bean, I think you're confusing "self-adhesive".

Can get up to 6 figures for a mint one.

It is because the British introduced the Postage Stamp and no one was using the system that British stamps do not carry the country name . All other postage stamps carry the name of the originating country of the posted item , even if used internally