With Foundations Small you can use Up to 3 URLs with up to 2 Keywords/Keyphrases per URL.

HOTH Foundations Medium & Large we accept the exact same inputs -
Up to 3 URLs with up to 5 Keywords/Keyphrases per URL.

You are not required to use all of them. As a rule of thumb, we encourage you to use all 3 URLs and not waste Keyword slots that you don't need to. Don't have 3 URLs? No worries. Many SEOs only submit 1 URL at a time with great success.

NOTE: All URLs and Keywords for any order must be in the same niche.

Otherwise, your content would end up looking like, "I enjoy driving my Lexus RX330 while studying Forex Trading and enjoying the best weight loss program." No bueno.