Using item category you can define 'units' for your invoices (For example, 'Period' for maintenance services) and set up each service or product sold as a dummy item, whether this is for a software licence or implementation services. These then can drive the accounting entries to the relevamt accounts.

As yet, I haven't hit any real snags in its use for a service business.

We plan to use 3x copies of FA in different countries (with different base currencies) and consolidate in a single base currency.