From In-Portal User Manual

The Pricing Options add/edit form has the following fields:

• Access Duration – this field, combined with the duration units, designates the length of the membership’s duration. If left blank, the membership is considered permanent. The group membership expiration is set based on this field’s value when the order with the subscription product is approved.
• Access Duration Unit - this field, combined with the duration number, designates the duration of the membership.
• Description – the description, as it will be displayed on the front end on the product details page in the pricing options section.
• Price – the subscription price for selected duration.
• Primary – the checkbox indicating if this pricing option is primary (the primary pricing is used when a user clicks on the “Buy now” link on the front end without going into the item’s details). The ‘Primary’ checkbox can not be un-checked, since this could leave the product without primary pricing. If you want to make another pricing primary, edit that pricing and check the ‘Primary’ option there. The first pricing option created is automatically assigned the primary status.