The Lagos bus operator aonda.pt is again this year operating a summer evening service.
The main service linking Meia Praia with Porto da Mós via the centre is operating in July and August.
Link to the timetable:
http://www.aonda.pt/templates/onda/images/horarios/OndaVerao.pdf
Lines 1 (circular), 3 (Lagos – Odiáxere) and 4 (Lagos – Luz (Praia da Luz) – Almádena – Burgau) will operate until 24h00, with line 6 (Lagos – Bensafrim – Barão de São João) operating till 22h00.