Your license allows you to install LR on your desktop and laptop but only to use one at a time.
The way I do this is to store all of my LR files in Dropbox (you could use any cloud drive, I guess but I'm only familiar with Dropbox).
This is not a problem if you are very careful. You have to be absolutely sure you have allowed time for the LR files (LRCAT, previews and smart previews) have updated before you shut your mac down. And when you use the second mac, you have to wait until you are sure the LR files have updated before you launch LR. If you do that, it will be the perfect way to use both macs with LR. There is always the chance you will mess this until you are used to the process, so I suggest you always back up as you close LR. If you launch too early on the second mac, you will get a conflicted catalog file...not the end of the world but you can lose a little work that way.
A lot of people smarter than I am think this method is not a good idea, so just realize you run some risk of creating a catalog problem if you are not very careful, but I thought that since I use the iMac and macbook pro about equally it was worth the risk. You have to make that decision yourself. If you do go ahead...did I say BACK UP ... Back up A LOT at first and you will be able to sort it out.
Lightroom is designed as a single-user, single-computer management system.
The easiest way to share the catalog between multiple computers is to put the catalog (and previews) on an external drive and move the drive from computer to computer as needed.
Smart previews are handy for not having the original files to access (for example, the original images are on a disconnected external drive), but they don't help with the shared catalog part.
Sharing the files and "edits" with your mobile devices involves some file transfer tricks for the images and lots of limits of the type of edits that are available on the mobile devices.