According to MagneticOne licence agreement one license (purchased module) can be used on one site, domain or server only.
If you have other domains/subdomains pointed to exactly same directory - they will be added to the license list free of charge, please request them to be added during product purchase or as additional ticket.

If you need this module to be insllated on other site, domain or server you have to purchase another licence.

Also MagneticOne offers "module packs", which include set of different modules and can help you save your money. Please review store for more details.