a question regarding licenses

[kddxb]

Thirteen years ago, I saw a commit that changed the open source license from GPL to BSD. What was the reason for this?

[veelo]

Originally, Coin3D was dual licensed under the GPL and a commercial license. The commercial license was "source included", so that commercial clients were able to make any changes they wanted. There was a clause in this commercial license that, should Coin3D ever be discontinued or its distributor go out of business, the last version would be relicensed under a permissive Open Source license, to reduce the risk for these commercial users that they would be stuck with a stale version of Coin.

13 years ago, that actually happened, and that is why the relicensing to BSD was done. Today Coin is being maintained by a small group of [non|for]profit users. See also the main page of https://www.coin3d.org/.