You have 2 options - both are a simple process if you have Paid in Full memberships in an old software that you need to transfer over to CHIP.
Option 1:
Step 1 - Click "Add Membership" on person's account
Step 2 - Locate the membership and assign for free. They've already paid for it in your old software, so no need to set-up payment.
Step 3 - Adjust expiration date to renew date
Done.
Option 2:
Step 1 - Click "Add Membership" on person's account
Step 2 - Set-up Payment on a Paid in Full membership
Step 3 - Assign Free Trial until renewal date
Note: this option will cause the membership to auto-renew after the free trial ends.
Done.