Hi Mayur,
Please refer to PMI Exam handbook which was updated on 1 April 2019.
www.pmi.org/-/media/pmi/documents/public...ssional-handbook.pdf
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Whether you register with PMI for the first or second time, you need to be eligible for the PMP certification. On page 6, you will find the eligibility requirements and on page 8, it showed you how you report your hours in your application. Page 14 talks about PMI audit process, if you are randomly selected for audition, then PMI will need to validate your project hours.
The current PMP exam content is based on PMBOK 6th edition. I think your 2015 training would have been based on PMBOK 5th edition? And so it may not be valid. However, I may be wrong, therefore, I recommend that you check with PMI to confirm.
After reviewing the handbook, if you have further questions, please post it in the forum. I will try my best to answer and to help you in your PMP certification journey.