Let me see if a got it.

You by a piece of land. You donate it to your children. They become the legal owners. You keep the right to use it for a determined period of time or until you die (it's just an example).

The legal owner of the land, in this example the children, will be able to sell it but you don't lose the right to use it since they're different rights over the same property, no matter how many times it changes owners.

Imagine that you have a plot and your house is on it. Your leaving the country in one year and you need money. You can sell the land but keep the right of use of the land for another year. You get the money now for the land (lower value that you you sell the land with full use of it) and the buyer makes an investment that will only be profitable after one year. The house is included in the business.

Or imagine you have a plot where you can build a factory. You not interested in building that but some company is. You keep the land and give them the right to build and use the land for 20 years. After that period, the right of use reverts to you. But the land as always yours. It's similar to renting a store or an apartment, with necessary adjustments.

But my advice is to consult a lawyer, preferably with a specific situation, since they are best qualified to help you on this matters.