i want to purchase online the Adobe Lightroom from link
https://creative.adobe.com/en/plans?single_app=photoshop-lightroom&store_code=in under the tab Individuals at price Rs 5988/Yr.
here i want to know what would be the annual upgrade cost ?
There is no annual upgrade, you pay 499/month for as long as you want to use Photoshop and Lightroom and you always have the latest version.
Since you're paying Rs 5,988 annually, perhaps you mean the annual renewal cost?
The renewal cost will be the same each year: Rs 5,988 per year, every year, unless Adobe adjusts the price but they have given no indications that the price will change yet.