Lightroom

Are you wanting to use Lightroom Classic? You posted this question in the forum for Classic. If you want to use either Lightroom, or Lightroom Classic on a desktop computer you need a subscription from Adobe. https://www.adobe.com/creativecloud/plans.html

It depends on the subscription your purchased. Obviously, you can purchase the Lightroom Plan or the Photography Plan from within a browser on a tablet too, but if you purchase the 'Premium' subscription from within Lightroom mobile, then you buy a subscription that is only for Lightroom mobile.

Becuase a tablet subscription gives you license to use it on your tablet; it does not give you a license to use the desktop version.