To access the Rebate analytics functionality in Tableau CRM for Manufacturing, you need two licenses:
Manufacturing Analytics Plus and Rebates Management Add on. Manufacturing Analytics Plus is a license that enables you to use the Analytics for Manufacturing app, which provides out-of-the-box dashboards and reports for sales agreements, forecasts, targets, and rebates. Rebates Management Add on is a license that enables you to use the Rebate Management feature, which allows you to create and manage custom rebate programs, automate payouts, and review processes. Together, these licenses allow you to perform what-if analysis, monitor program performance, and collaborate with channel partners using Tableau CRM for Manufacturing. References: Rebate Management - Salesforce Help, Salesforce Manufacturing Cloud Rebates What-If | Tableau Exchange, Streamline Channel Sales with an Intelligent Rebate Strategy - Salesforce

Explanation
To export Account Based Forecast data to use in their Demand Planning system, the user can use standard Salesforce Reporting to create a report with only forecasting quantity data, including any sales team adjustments. To do this, the user can perform the following actions:
Create a report using the standard report type of 'Account Forecasts with Product Period Forecast'. This report type allows the user to access the data from the AccountForecast and AccountProductPeriodForecast objects, which store the forecast metrics for each account and product combination.
Add the 'Adjusted Forecast Quantity' field from the 'Account Product Forecast' object to the report.
This field shows the forecast quantity after applying any adjustments made by the sales team. The user can also add other fields, such as account name, product name, period name, or forecast set name, to the report as needed.
The user can then run the report and export the data to a CSV file or another format that can be used by their Demand Planning system.
References:
Create Holistic Forecasts with Advanced Account Forecasting > Use Advanced Account Forecasting Analytics for Manufacturing > Create Reports and Dashboards for Advanced Account Forecasting AccountForecast | Manufacturing Cloud Developer Guide
[AccountProductPeriodForecast | Manufacturing Cloud Developer Guide]

The renewal days for sales agreement is a setting that defines the number of days before the end date of a sales agreement to mark the beginning of the renewal period. Users can renew a sales agreement only when the renewal period starts. This helps to plan ahead and negotiate better terms for the next sales agreement1. References: 1: Define Renewal Period for Sales Agreements | Salesforce Help2

Explanation
A sales agreement is a record that captures the terms and conditions of a long-term or run-rate business relationship between a manufacturer and a customer. It can include products, product categories, prices, volumes, schedules, and other details. A sales agreement can have a maximum of 1500 products or product categories and 72 schedules. Contact Salesforce support if you want to increase the limits. Note that having a large number of product or product categories and schedules can affect system performance1. References: Considerations for Working with Manufacturing

Explanation
When an org hits the account product period forecast record limit, new products cannot be added to account forecasts automatically. This means that when a user recalculates a single account forecast or all account forecasts, the new products are not added to the forecast. Also, if a user manually adds a new product to an account forecast, the product will not be included in the forecast calculations. The user will see a warning message indicating that the product is not calculated. Toresolve this issue, the user can contact Salesforce Customer Support to request an increase in the limit. References: Salesforce Help: View the Data Volume Usage, Defined Limits, and the Percentage of Limit Used for Account Forecasts, Salesforce Help:
Considerations for Working with Manufacturing