If Adalysis encounters an API access issue, you will see the following warning on the account dashboard:

If this account is within an MCC linked to Adalysis, it's most likely that the account revoked access to the MCC.  You will first need to reconnect the account to the MCC in Adwords before Adalysis can access this account.

If however, this account is not within an MCC, and you have unintentionally revoked the API access permission Adalysis had, you can reinstate it by logging out of Adalysis (as shown below) and re-login.  

You can see which apps have access to your Adwords account within your Google's account security settings.