When you buy a painting you do not acquire the right to make copies of it or use it in any commercial way.

Generally the rights of reproduction remain with the artist unless you specifically purchase them, which is uncommon.

The artist may make, and sometimes already has made,  prints of the artwork, greeting cards, postcards, etc.  This is not uncommon, is one of the usual rights of copyright, and is one reason artists can sell a painting for what they do .  

It is not necessary to spell this out, but as a means of avoiding future misunderstanding we do so.

It does not mean you cannot take a picture of your painting and show it to your friends.   It does not mean you cannot have your house featured in Architectural Digest and have the painting on the wall (We hope you do!!!)  Please attribute if you can!

It does mean you cannot make copies of it or use it in an advertising campaign or any other commercial use, without permission from the artist.