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 using the form below: Enter your email — the one you used when placing the order. We’ll send a 6-digit verification code (valid 10 minutes). Enter the verification code to confirm it’s you. Pick your license — the form shows the eligible licenses on your account; select the one you’re activating. Paste your 63-digit Installation ID and submit. Your Confirmation ID appears on the page and is also emailed to you. Enter the Confirmation ID in Office to complete activation. Each license activates one device. If you’ve already used this license and need to reactivate after a fresh Windows install on the same PC, please contact support with your order number — we’ll review and grant a re-activation where appropriate. Email used for your order Send verification code 6-digit verification code Verify Which license are you activating? 63-digit Installation ID Get Confirmation ID 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”. “No eligible Office Pro Plus licenses found for this email” Cause: the email you entered doesn’t match any order with an Office Pro Plus license on this store, or your order is still being processed. Fix: double-check that the email is the one you used at checkout (it appears on your order confirmation). If you placed the order in the last 5 minutes, wait briefly and try again. If you still see this error, contact support with your order number. “This license is already activated. Please contact support to re-activate it.” Cause: a Confirmation ID has already been issued for this license against a previous Installation ID. Each license activates one device. Fix: if you’re trying to activate a fresh install on the same PC and your order is recent, contact support with your order number — we’ll review and grant a re-activation where appropriate. If you need to use the license on a different PC, please note that licenses are hardware-bound and don’t transfer — you’ll need a new license. 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 FilesMicrosoft OfficeOffice16 — 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 →