Is there any way to setup a yearly billing structure rather than monthly?
Annual Cloud pricing is calculated on a tiered basis (the same as monthly per user pricing), however annual cloud licenses are discounted as you are only charged for 10 months of the year, rather than 12 months if you were to pay on a monthly basis.
Atlassian have created this Cloud Pricing Calculator which allows you to calculate prices based on your user tier for the apps you are looking to purchase. When using this calculator, make sure to switch the 'Billing Cycle' toggle to 'Annual' (the default is set to 'Monthly').
To pay annually for Asset Management for Jira, you'll need to contact the Atlassian Customer Advocate team and complete this form.