Release a Paid Addon?

[nhawk]

As has been said, it depends on the software and the agreement when the mod was written.

Several of my custom mods, used only by who they were written for contain this clause..

2. Purchaser acknowledges that this is only a limited nonexclusive license. Snog's vBulletin Mods is and remains the owner of all titles, rights, and interests in the Software.

EDIT: A perfect example of this is my raffle system. It was written years before release on vB.org for one particular site. If that clause wasn't in the agreement, when the site went belly up I couldn't have released it as a free mod here on vB.org.

I would never have released it if the original site was still in existence, or without the original owner's permission if the site was still around. But I could have just because that clause was in there.