You do not need to distribute all of the resource licenses at once. If you decide not to distribute all of the resource licenses at one time, the unallocated licenses will be set aside for you to distribute at a later point. This could be helpful if you anticipate staff changes throughout the year.
When distributing licenses using the Equal Limits option, you can choose a lower number than the suggested amount of licenses per invited teacher. Alternatively, you can use the Custom Limits option to distribute a portion of the resource licenses to your teachers.