Select a suitable licence for your data
The most commonly and widely used data licences are the suite of Creative Commons (CC) copyright licences which clearly describe how data can and cannot be reused. The CC licences are irrevocable. This means that once you receive material under a CC licence, you will always have the right to use it under those licence terms, even if the licensor changes his or her mind and stops distributing under the CC licence terms. Of course, you may choose to respect the licensor’s wishes and stop using the work, but once a dataset has been issued a CC licence, it cannot be revoked afterwards.
A scientific dataset, which other researchers may build upon or which is published together with a scientific article, is usually published under the CC-BY licence. More on data licences on HOW TO FAIR and openmod.
If you do not wish to share your data, it is nevertheless highly recommended to make your metadata open.