How do I cite an ebook without page numbers in-text in APA format?
The APA Publication Manual says, on pages 171-172, you should include author, year, and other identifying information for quotes when there are no page numbers. If there are paragraph numbers included in the text use those with the abbreviation "para." For example, (Smith, 1978, para. 3). If there are headings in the document use those in your citation. For example, (Smith, 1978, Introduction section, para. 5). If the heading would be too large to include the whole thing then use a short title with quotation marks. For example, (Smith, 1978, "The Future of Libraries," para. 1).
More information on citing ebooks can be found at the APA Citation Style Blog.