use a server side scripting language to count installations

[jneumann]

Instead of sending everyone that installs a toolbar to a page that says:
"You have installed a toolbar with Developer License. You will be redirected in a few seconds.

If you are not redirected automatically then click here."
Use a language like php to count the installation and redirect to the firstURL page without it ever being seen by the end user.

[Admin]

Developers License is a Trial version for 500 installations
In order to remove that message you should buy Standard or Business License.