So instead of going through specifications, offer, purchase order, invoice and license delivery, we can offer alternatives.
First, you can order license with updates for several years included. This way you don't need to come back every year for a license update.
Second, we can setup a software maintenance contract. This gives you a subscription for the plugins you need. We would send license keys and invoice for initial purchase or when old keys expire. If you need help with using a plugin, your support requests gets priority and of course billed. On the month end, we send an invoice for development time. The contract defines rates and availability.
If you are interested, please contact us.