Implications for switching licenses mid-stream

Arnoud Engelfriet arnoud at
Tue Apr 22 06:12:33 UTC 2008

Jon Lesser wrote:
> Many people have already downloaded our software with license X. Can  
> those people continue to use what they've downloaded under the terms  
> of X even after we change the license to Y?

Yes. Of course they can only use the *new* version under license Y,
but the license you granted in the past is perpetual (assuming they
don't violate it).

Backfeeding improvements from the version under license Y to the X version
is not possible for those users, unless you explicitly relicense or
dual license some improvements. For example, you could make security
fixes available under a dual license so that users with the old version
at least are not vulnerable to that kind of bug.

And by the way, you need permission from all contributors to switch
to Y, but you probably knew that.


Arnoud Engelfriet, Dutch & European patent attorney - Speaking only for myself
Patents, copyright and IPR explained for techies:
              Arnoud blogt nu ook:

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