Just use the advice given above by scott931: (slightly amended to put all steps in)
1. Open your LastPass Vault
2. Click on Account Settings
3. Click Never URLS
4. Click. 'Add'
5. Pick 'Never Do Anything' from the Type Dropdown Menu.
6. for the URL use: bulksell.ebay.com/ws/eBayISAPI.dll (customise the first bit for your region - I'm in the UK so used bulksell.ebay.co.uk/ws/eBayISAPI.dll)
7. Click 'Add'