How long are the terms for invoice apps?

[iMore Question]

When you install an invoice app (example: invoice2go, invoicemaneger, or quickbooks) on an iPad do you need to keep paying every month or only once? Where can you find the term agreements for an app? (example: how many days you are paying for ect.?)

 

[cmrobbins42]

When you install an invoice app (example: invoice2go, invoicemaneger, or quickbooks) on an iPad do you need to keep paying every month or only once? Where can you find the term agreements for an app? (example: how many days you are paying for ect.?)

Invoice2go - Invoice App Pricing | Invoice2go

Invoice Manager - Mentions "* One time payment fee, no renewal subscription and no Internet required. " [URL="https://itunes.apple.com/us/app/invoice-manager-create-send/id611689580?mt=8&at=10l3Vy]https://itunes.apple.com/us/app/invoice-manager-create-send/id611689580?mt=8[/URL]

QuickBooks - QuickBooks Pricing