In general you cannot place your work under public domain because in many countries (including in the U.S. with some exceptions) the work must enter the public domain by itself after the copyrights expired. The copyright term also differs of course from country to country. Even worse, there are jurisdictions in which the public domain is not recognized.
> Even though SQLite is in the public domain and does not require a license, some users want to obtain a license anyway. Some reasons for obtaining a license include:
>
> * You are using SQLite in a jurisdiction that does not recognize the public domain.
> * You are using SQLite in a jurisdiction that does not recognize the right of an author to dedicate their work to the public domain.
> * You want to hold a tangible legal document as evidence that you have the legal right to use and distribute SQLite.
> * Your legal department tells you that you have to purchase a license.
>
> If you feel like you really have to purchase a license for SQLite, Hwaci, the company that employs the architect and principal developers of SQLite, will sell you one.
