1p Mobile has changed its Terms and Conditions and now costs £2.50 per month. (I've just left)
If you signed up to 1p Mobile before the 1st January 2021, a minimum spend of £2.50 per month will apply on your SIM card. This monthly minimum spend requirement does not apply to customers joining 1pMobile on or after the 1st January 2021. However, you’ll need to top-up your phone with at least £10 of credit every 120 days.