hi i have just made a payment of rs 75 to purchase i cloud storage but it didn't update yet on my storage

If you have upgraded iCloud+ plan, once your request for iCloud+ plan has been activated, you should receive an invoice in your email box.

Then check -> Go to -> Settings -> your name -> iCloud -> if you see 50 GB (or 200 GB or 2 TB) then you have an iCloud subscription.

If you have an iCloud+ plan subscription, you will receive a monthly bill from Apple, check your email box.

See also the following Apple articles:

What's the difference between device storage and iCloud storage?

What's the difference between device storage and iCloud storage? - Apple Support

How to use iCloud on iPhone -> How to use iCloud on iPhone – Apple Support (UK)

Manage your iCloud storage -> Manage your iCloud storage - Apple Support