We had a similar question in our organization where I answered as follows:
1. Whether or not we include freelancers is a decision of your best judgement. Do you think the person should be involved with our entire organization and be able to interact with other roles frequently? Then this person should have a glassfrog account. Will this person regularly participate in the Tactical and Governance Meetings? Then too should this person receive a glassfrog account.
2. If the person doesn't necessarily need an account: A solution could be to create a role which coordinates with freelancers. Let's say your circle uses several freelance designers. They maybe don't each need a glassfrog account. Instead it could make sense to create a role which is responsible to interact with these designers, negotiate contracts, monitor results, etc.