Abell, known as a specialist in franchising, was on a business trip to the city with his London colleague, corporate partner Christopher Jackson.
Jackson was released from his room at about 5.00am GMT Friday and Abell about one hour later.
In an email to Managing IP, the IP lawyer said he was "glad to be a free man".
While trapped in his room, he had been interviewed on the BBC's Today programme on Thursday morning.
In an emotional interview on Friday morning, after being released, he told the presenter he was pleased to be free and paid tribute to his rescuers and the hotel staff.
