The license is registered to you as a person. So long as you keep it only on a portable owned by you you can use the software. I use CCleaner Pro portably, using portable.dat from the free portable zip. Autoupdate works perfect and even installs both the 32bit and 64bit versions into the portable folder.
[biased opinion] I wish more softwares would make their pro install so easy for portable versions [/opinion]