If while trying to activate the key, its showing activating... then just allow the extension in incognito mode and try again, here is how.
Right click on the extension and click Manage extension
Allow extension to run in incognito, so we can install app without worry of other extension causing trouble
Now just open Incognito Tab then open blurweb.app
and click on the extension to enter the license key
If still facing any issue let us know via chat widget or mail at firstname.lastname@example.org