What is created when an owner conveys property but reserves the right to use a portion of that property?

When an owner conveys property while reserving the right to use a portion of that property, this situation results in an easement by reservation. An easement by reservation occurs when the seller retains the right to use a specific part of the property they are transferring, allowing for a specified use that does not interfere with the new owner's rights. This legal structure ensures that the previous owner can maintain access or utility over the reserved portion, regardless of the sale.

In contrast, an easement by necessity typically arises when a landlocked property requires access to a public road, which is not the case here, as it focuses on necessity rather than reservation. A lease agreement involves a contractual arrangement where one party rents property from another, which does not apply to the situation of conveying property with reserved rights. A right of first refusal is a contractual agreement that grants a party the first opportunity to purchase property if it becomes available, but it does not create any physical use rights on the property itself. Thus, the most suitable choice in this scenario is the easement by reservation.