Hi, @Jaiprakash Mistry Welcome to Microsoft Q&A, Thanks for posting your query,
I understand that you would like to know the pricing for Redis cache premium - p1 and reservations for the same, correct me if my understanding is wrong.
Can you please share where you are seeing It says 55% savings with cost of $91 per month per node
The link below with the cost of reserved instance and how much savings you will get if you chose this option, on the pricing page you can find the cost per node
~55% savings is correct for a 3Yr reserved pricing and assuming 31 days in a month - the monthly on-demand/pay-as-you-go price is also right ($412/month). For the same P1 SKU, your monthly cost will be $186 if you go for a 3Yr reserved pricing.
Pricing - Azure Cache for Redis | Microsoft Azure
Please let us know if this helps.
Regards
Geetha