If you are using Photoshop CS6, I believe Adobe allowed you to install and run the software on two computers, provided they both used the same OS (either Windows or Mac) and you personally owned both machines. You were not allowed to activate the same license on a Windows PC and a Mac simultaneously.
Typical installations at the time assumed you'd install Photoshop on a laptop when you were on the move and the other on a desktop PC when you returned to base. With these specific provisos, CS6 and possibly earlier versions, could legally be run on two machines (but probably not at the same time).
In the event you had reached your 2-machine limit, or simply wanted to upgrade to a faster PC, you could Deactivate Photoshop on the old machine, then Activate it on a new machine, as the link below describes:
https://www.livelaptopspec.com/how-to-move-adobe-photoshop-cs6-to-another-computer/
Given Adobe's predeliction for moving from perpetual licenses over to subscription licensing, I would tread very warily before attempting to Deactivate Photoshop on your old machine. You might end up with no Photoshop functionality.
But if you still have the original installation files or DVD, plus the license documentation and (hopefully) the bill of sale or till receipt (to prove to Adobe it's legitimate) then you might consider installing Photoshop on a new computer and trying to Activate it. This might involve talking to Adobe on the phone. Best of luck!
This assumes Adobe haven't "done the dirty" and changed their Activation Servers to revoke attempts to activate old versions of CS6, et al. Cracked versions of Photoshop abound and Adobe annoyed many legitimate users of CS4, CS5 and CS6 by marking their legitimate licenses as Invalid, which caused a huge uproar in the community. You'd switch on your PC and start Photoshop, only to be greeted by a message telling you your software was pirated and had been disabled.
For more details, search the Adobe forums. You may find it's still possible to Activate CS6 on a new machine, provided you have a legitimate license purchased directly from Adobe or one of their official resellers. Adobe removed the CS6 installation files from their download servers some years ago, so any copies of CS6 you find purporting to be "genuine" or free, are nothing of the sort.