The last step of influencer marketing is to measure and optimize the results of your campaign, and evaluate the performance and impact of the influencers. To do so, you should track metrics relevant to your goals and objectives, such as impressions, clicks, conversions, sales, or brand awareness. Utilizing tools and platforms like Google Analytics, social media analytics, or influencer marketing platforms can help you monitor and analyze the data. Additionally, collect feedback from both the influencers and the audience to get an understanding of how they perceived and responded to your campaign. Ask for testimonials, reviews, or case studies from the influencers that can be used to showcase success and credibility. Based on the metrics and feedback, optimize your strategy to identify what worked and didn't work, as well as what can be improved or changed for future campaigns. Lastly, maintain and nurture your relationship with the influencers by thanking them for their collaboration and contribution.