If you cancelled your account by accident, or if you change your mind anytime before the next billing cycle or your time is up, you can un-cancel your account.
For monthly accounts, "time's up" is before your next monthly bill.
Meaning, if your plan renews on the 15th of every month, and you cancel your account on the 6th, you would have access to your account until the 15th of that same month. If you cancelled after the 15th, you would have access to your account until the 15th of the NEXT month.
For yearly (annual) accounts, "time's up" is before the end of your account year's time.
Meaning, if your plan started February 15, 2020, and you cancel in July 2020, you would have access to your account until February 15, 2021.
To un-cancel your account
Step 1: Log in. Near your picture and name in the top, right-hand corner, click on the Down arrow and go to your Billings page (yellow highlight in screenshot below).
Step 2: Click the date on which your account is due to be cancelled.
Step 3: Click RE-SUBSCRIBE (circled item in screenshot below).
Your account will now be reactivated.