Yes you may. There is no restriction in using the system this way. In fact it’s part of our solution offering to assist you to test your products in other regions first without spending anything more on IT needs. All you have to do is to configure prices in required currency and choose desired currency while creating new invoices. Various transaction screens/ reports allow you to filter data for specific currency.
However different country requires different reporting needs (like separate report header with address/ contact numbers/ company & tax registration numbers etc.), product/ package availability, security rights for staff operating in that country, stock tracking, logistics service provider integration, statistical analysis/ business intelligence needs etc. Such requirements are supported in higher licenses only. You may choose to upgrade when such features are absolutely necessary.
For example if you are operating in 10 countries and require different tax structure/ reporting needs for 3 countries. You decide to issue common invoices from head-office for all sales in remaining 7 countries then you may just upgrade for Enterprise eUnite license that allows you up to 3 Business Centres. Plan wisely, be smart and cut down your IT spending.