You can go to your products page to look at your serial number:
Adobe ID
If the platform is Multiple the number should work for Mac as well as for Windows.
The installers for Premiere and Photoshop elements are here:
Download Adobe Premiere Elements 15, 14, 13, 12, 11, 10
Download Photoshop Elements | 15, 14, 13, 12, 11, 10
I don't have Elements, but in the pre-CC app days you would authorize or deauthorize a computer for use with the program. If you never plan on using the Windows version again you should look in the program for some way to deauthorize that computer, so that you still can install it on two computers. Or don't worry, you should be able to have it on both the old PC and the new MacBook Pro. If the serial number is multiple platform.
If it's platform specific then I'm not sure what your options are! There is a discussion here that might help:
Transfer License from PC to Mac