Depending on a "ProductId" a certain conversion label will be send to Google, I use a lookup table to fill in this value. Now what happens if my customer has 3 products (with different conversion labels) ? How to solve ?

[steve_lake]

With a lookup table, the first match will be the one that gets used. In your scenario, if a customer has three products with different conversion labels, obviously this will not be satisfactory. To solve this, you would need a custom javascript extension which checks each ProductId in the list, if there's a match, send the correct conversion event, then move on to the next one. If you need any assistance with this please contact your account administrator or support team. Many thanks Steve Lake