Why use a license agreement rather than a lease for renting space?

Depends on why you need to use the space. Licenses by definition are for an indefinite period that either party technically should have the right to cancel at any time. Leases typically have a specified time/term. The "Licensor" (the "landlord" under a license) retains control this way, to terminate the relationship if things aren't going well, without having to go to court for an "eviction" (as long as state or local law doesn't require an eviction regardless of the kind of arrangement the document says it is. Licenses usually also don't have as many legal provisions and are for really short periods of time. For example, if a movie company wanted to shoot a scene on your front lawn, a license would be more likely the document because it would give the homeowner the comfort that if things were going badly he or she could simply tell the movie people to get off the property. It is something better than an oral arrangement too, because without the written agreement the "Licensee" (the "tenant" of the license) might claim greater fixed rights like a lease.