Yes, there is a 10-day grace period for commercial Bitrix24 Cloud accounts that weren't able to renew subscription for any reason (updating card information, expired card, pending wire transaction, etc.). During the grace period, Bitrix24 accounts remain active and do not roll back to the Free plan. The 10-day grace period is enabled automatically after your commercial subscription gets expired.
Please note that the grace period is not activated after your free 30-day trial is over.