How much is Bubble membership?

Could you kindly clarify for me the cost associated with Bubble membership? I'm quite interested in joining but I'm not entirely sure of the financial commitment involved. Is the membership fee a one-time payment or is it recurring? Also, are there any additional costs or hidden fees that I should be aware of? I would appreciate it if you could provide a detailed breakdown of the costs involved so that I can make an informed decision. Thank you in advance for your assistance.