Install the application on your system to a location visible by all users:
Windows: 'C:\Program Files'
macOS: '/Applications'
macOS: '/Applications'
...so that each user can run it from a single location. Then, each user should run the application from his/her own account and fill out the registration dialog. A unique license file is then created for each user. Moreover, each user has own application assets (brushes, papers,...).
One account,
many possibilities