Bought and installed 10.7 on iMac months ago.. do I need to pay again for Macbook?

So as the title says, I bought and upgraded 10.7 for my iMac desktop, and figured today that i'd get my laptop updated as well. When I went to the store in the laptop, logged into my normal appleID, there was no "download again" option or anything for 10.7, there was just the price of $29.99. Do they really require you to purchase the OS seperatley for every computer you use? Or am i missing something here?

Thanks a lot, If you need any information I'll try to get it to you.

thank you so much! problem solved.