You can purchase an additional/several social profile/s for your Iconosquare account. 

Under a STARTER plan, an additional profile is $9. 

For a PRO monthly plan which already gives you an allowance of 3 social profile for $39, any additional one is $19/ per month.

For the ADVANCED plan, which has an allowance of 5 social profiles for $79, any additional one is $29/month.

For more slots, you can either upgrade your plan or subscribe to additional profile(s).

Also known as "What is the price of an additional slot for my social profiles?"