Pro accounts are charged by the number of rental units in their account. You can view the calculator at the top of the Pricing Page to explore rental unit pricing.Units for the 30-day account and monthly account are about $3.50 per additional unit. Units for the Yearly account cost about $7.50 per additional unit. Units for the Lifetime account cost $20 per additional unit. Please note: The more units that are added the more of a discount you get on your unit additions.