How to Install and Activate Office 2021 Professional Plus (Step by Step)

Activate Office 2021 Pro Plus in 4 steps. Open the download below → install → choose phone activation → submit your Installation ID using the form on this page. About Office 2021 Pro Plus Office 2021 Professional Plus is a perpetual-license edition of Microsoft Office — one payment, no monthly subscription, and you keep the software for as long as your PC runs Windows 10 or 11. It includes Word, Excel, PowerPoint, Outlook, Access, Publisher, and OneNote as classic desktop applications. Office 2021 introduced features buyers asked for from the earlier 2019 release: dynamic array functions and XLOOKUP in Excel, a modernized Outlook calendar with shareable invites, improved Inking in Word and PowerPoint, and a refreshed user interface across the suite. It’s a stable, offline-capable Office you pay for once. This guide walks you through the full activation flow. It takes about 10 minutes end to end. If your key won’t activate after following the steps, see Troubleshooting below or open a support ticket. What you’ll need before starting Your license key from the order confirmation email we sent you (subject line: “Your ActSoftware order”) A Windows 10 or Windows 11 PC with administrator rights At least 5 GB of free disk space An internet connection to download the installer (the activation itself does not require internet) About 10 minutes of uninterrupted time Step 1: Download Office Use the following link to download the official English .img file of Office 2021 Professional Plus from Microsoft: Download Office 2021 Professional Plus Step 2: Extract and Install Once downloaded: Install Winrar (download here) and extract the .img file, or double-click it to mount it in your system. Run the setup file and install Office. When prompted, enter your serial key. At the activation screen, select “I want to activate the software over by telephone“ Click “Next” to continue to Step 3. Note: No actual phone call is required. Step 3: Get Installation ID In the new window: Select your country Make note of your Installation ID Step 4: Submit Installation ID Complete these final steps: Enter your Installation ID in the form below We will provide you with a Confirmation ID which will be sent to your email Enter the Confirmation ID to complete activation Email Address: Enter the email address used for your order Order ID: Enter your order ID (numbers only) Installation ID: Enter your 63 digit Installation ID Submit Troubleshooting “The product key you entered isn’t valid” Cause: the key was mistyped, or whitespace was copied from the email. Fix: copy the key carefully (no leading/trailing spaces), or open the order email, select the key, copy, then paste using Ctrl+V. Activation wizard skips straight to “Sign in with a Microsoft account” Cause: Office is trying online activation, not phone activation. Fix: close the dialog, open any Office app (Word), go to File → Account → Change Product Key, enter the key, and at the activation screen choose “I want to activate the software over the telephone”. The Installation ID form on this page returns “key not found” Cause: your order is still being processed, or you entered the wrong key. Fix: wait 5 minutes after payment confirmation, or contact support with your order number — we’ll match the key manually. Confirmation ID doesn’t activate Office Cause: an extra character or digit was missed when copying. Fix: copy the Confirmation ID directly from the email — don’t retype it. If it still fails, contact support and we’ll re-issue a fresh Installation ID + Confirmation ID pair. Office activates but says “Product without license” later Cause: rare licensing-cache issue. Fix: open Command Prompt as administrator and run cscript ospp.vbs /act from C:\Program Files\Microsoft Office\Office16 — or just contact support and we’ll send a replacement key under the 30-Day Replacement Guarantee. Frequently Asked Questions Is this a one-time purchase or a subscription? One-time. Pay once, keep Office forever (or until the underlying hardware retires). There’s no annual renewal, no expiry, and no recurring charge. Can I install this on a Mac? No. Office 2024 Professional Plus is a Windows-only product. For Mac, see Office 2024 Home & Business for PC/Mac or one of the Mac-specific editions. Can I transfer this key to another PC later? No. The license is bound to the device you first activate it on. If you switch PCs, you’ll need a new key. (Windows licenses behave differently — they can be re-linked to a Microsoft account and moved to new hardware. Office desktop keys cannot.) Do I need internet to use Office after activation? No. After phone activation, Office runs completely offline. You only need internet to download the installer or to sync with OneDrive (which is not bundled here). What’s the difference between Pro Plus and Home & Business? Pro Plus includes Access (database) and Outlook with full business calendar features. Home & Business has Word, Excel, PowerPoint, OneNote, and Outlook — but no Access. Should I upgrade to Office 2024 instead? Office 2024 is the newer perpetual release and receives security updates further into the future. If you’re starting fresh, Office 2024 Pro Plus is worth considering. If you already have 2021 installed and working, there’s no urgent reason to switch — Office 2021 receives mainstream support through 2026 and extended security updates through 2031. Related products Office 2024 Pro Plus Newer perpetual release — security updates further out Office 365 Pro Plus 5 devices, lifetime account, 1TB cloud included Windows 11 Pro Transferable to new hardware when linked to your Microsoft account Wondering whether ActSoftware is the right place to buy from? See why thousands of buyers trust us →