I don't understand your question. When you buy Stedmans it comes on a disc (I suppose you could probably buy it online and just download it too). You sync it to your pda. So there shouldn't be a reason why you couldn't use it on another pda.
I know that, in general, programs that you have on one palm are easily transferrable to a new palm (as long as the same name is the registered user), but I don't know about specific programs... Also, I have no idea about pocket pc's or other PDAs...
I've had Stedman's Palm and PPC versions, and had to transfer both from an older PDA to a newer one. Works fine, as long as you have the serial number.