All files on Brushportal.com are licensed under licenses determened by the artists. Therefore, always look at License field on download page to be sure of permitted use of the file. Most of the files also contain license "Read me" file, so be sure to check that out as well.
If you are unsure about what each license means, on this page, in plain, simple language, you can read everything about Creative commons (CC) licenses permitted use and conditions.
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