Sunset Clauses in Software

DaveAtFraud writes: "Ed Foster over at InfoWorld has an interesting column on "sunset" clauses in commercial software. I don't have a problem with people who write, say, anti-virus software charging for a "subscription" to their virus signature update service. I am paying for something of value to me and it costs them something to maintain this data. I do have a problem with the same people extracting a little extra "squeeze" every couple of years and forcing me to learn yet another user interface just because they have decided that the old one looks little dated. Somehow, I don't buy (no pun intended) that their engine for scanning a byte stream has changed again."