Use a powerful quote
Using quotes in your concluding statement may sound cliche, but it is both memorable and powerful. However, not any quote will suffice. Always be certain that your quote is related to the issue. If you're making an argument, you might wish to include a quote that emphasizes your main point, either directly or indirectly.
Assume you're giving a presentation about your company's mission statement. You might use a Powerpoint presentation to give the material, and your final slide could include an uplifting remark.
Quotes are beloved, and they give a pleasant conclusion. However, make sure that your quotation fits the tone and purpose of your speech.