Hello Do i have to purchase 2 lic if i intend to use the product on the desktop and the laptop ? I sure will be using only one machine at a time , both machines are mine and no one else will be using .

No, you then need just 1 license. If you purchase 1 license, at any given moment, 1 person is allowed to operate the designer. If you're the only person there, you thus need just one license