You know the uneasy feeling: You’re not quite sure that you’ve parked legally, but you’re already 10 minutes late for dinner, and you just don’t have the stamina for one more go around the block. WhereToFindParking.com subscribers in Boston can calmly pull over, launch an Internet browser from a cellphone, and check if a certain spot is in the clear or look up other area parking options. The site’s cheapest monthly subscription package with cellphone access costs $12, which seems expensive only until you return from your meal to confront another $40 ticket.