azslow3
For XLN I have not found such explicit statement, and there are cases when reactivation of computer which was active before is problematic (Pianoteq). So I have asked XLN about that. It happens that it works close to the same way as with Melodyne. You can reactivate the computer you deactivated before (I need at least 2 activations at home and want activate notebook instead when I travel).

azslow3
About Melodyne. They especially mention that you can activate/deactivate it on any computers when required:
From http://helpcenter.celemony.com/editor2/en/singletrack_tour_00.html :

Deactivating a computer: We allow you complete control over the allocation of your activation rights by allowing you the option also of deactivating computers. Suppose, for example, that you have already activated Melodyne on two computers but wish to use a third one temporarily. No problem: all you have to do is deactivate one of the computers currently activated. This will free up one activation credit, which will then be transferred to our server. You can use this then to activate the third computer. If, later, you wish to go back to your original pairing, just deactivate the third computer and reactivate the one you deactivated earlier.

 
For XLN I have not found such explicit statement, and there are cases when reactivation of computer which was active before is problematic (Pianoteq). So I have asked XLN about that. It happens that it works close to the same way as with Melodyne. You can reactivate the computer you deactivated before (I need at least 2 activations at home and want activate notebook instead when I travel).