Can I use an extended license image for resale on more than 1 product?

Yes, you can put the asset on multiple objects. The licence is per client, not per use. This would mean, that if you have one client wanting the asset on a mug, a different one wanting the asset on a t-shirt, you would need to acquire a licence for each of them. You need to count your use also in this scenario.

Look here for more information on licensing: https://community.adobe.com/t5/stock/links-for-licensing-terms/td-p/11366788
(Disclaimer: As always with licensing, this is my interpretation of the rules. I think they are correct and advice is based on reading and interpreting the licence terms and on fair use for both the buyer and the artist/stock company, but I cannot rule out that my interpretation is wrong. I'm not an Adobe employee).

Let me move this to the Stock forum for you, which I think is the appropriate forum for your question. My suspicion is that you'll need to talk to customer support about this. There are few if any lawyers here.

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