After buying the Batch Render&Relink start the 3ds Max and install the plugin.
For starting the registration run the Batch Render&Relink and choose the item "Activation" in the menu "Help".
Updating the license key:
The identification file must be generated on computer
where you plan use the plugin.
Please use your permanent e-mail box (same as you use at purchasing).
You can always restore the password on the page Restore password.