Apache 2.0 License.
The Pdfium2BMP requires native PDFium libraries. These are not included in the Pdfium2BMP NuGet package.
Pdfium2BMP is based upon work by Pieter van Ginkel, his library was licensed under Apache 2.0. Therefor Pdfium2BMP is licensed under the Apache 2.0 license. See the license details for how PDFium is licensed.