What is the AVASTLIC file format?
A file with the .avastlic extension contains license data used by commercial versions of Avast! antivirus software. It is a small binary token (typically around 2 KB) - not a plain-text file - and holds information about the user's subscription and Avast authentication data, such as:
- product name,
- username,
- license expiration date.
The license data inside is obfuscated and validated by Avast against its activation servers; tampering with the file invalidates it.
Obtaining and installing license files
Users who obtained a software license online usually receive .avastlic files as an email attachment. The license file can be installed by double-clicking it, prompting Avast to import the activation data automatically. After successful installation, information about the subscription can be viewed in the program's main menu. The license file's default name is License.avastlic. However, some Avast! software versions stored this file as License.dat - a plain .DAT file containing a license key that needed to be copied manually.
.avastlic files are largely a legacy activation method. Modern Avast products - Avast One and Avast Premium Security - activate via an online account and subscription rather than a local license file. Avast Software was acquired by Gen Digital (formerly NortonLifeLock) in 2022.
Security & safety
RISK: MEDIUMThe .avastlic file is license data, not a program, so opening it through Avast is safe and expected. The real cautions are: (1) treat it as private - it ties to your purchase/subscription identity and could be misused, so don't post it publicly; (2) never edit it - changes invalidate the license; and (3) beware scams: 'free avast license file', 'avastlic generator' or 'crack' downloads are a classic malware/piracy vector. Only obtain an .avastlic from Avast (your purchase email or Avast account). Also be wary of unexpected .avastlic email attachments from unknown senders.
Format details
in a nutshellPrograms that open AVASTLIC files
Windows1 app
Avast (Avast One / Premium Security / Antivirus)
Freemium Install Avast first, then double-click the .avastlic; Avast prompts to add the license - confirm to activate. Or use Menu > My Subscriptions / 'Insert activation file' to load it. Technical details
deep spec| Developer | Avast Software (Gen Digital) |
| Format type | Binary license/activation token |
| Typical file size | ~2 KB |
| Encoding | Binary; obfuscated - not readable in a text editor |
| MIME type | application/octet-stream |
| Associated OS | Windows |
| Default filename | License.avastlic |
| Installation method | Double-click to prompt automatic import by Avast |
| Stored data | License holder name, product name, expiration date |
| Validation | Verified by Avast against activation servers; invalidated by tampering |
| Security model | Obfuscated token bound to the subscription; not user-decryptable |
| Distribution channel | Emailed to customers as an attachment after online purchase |
| Alternative format | License.dat (older Avast editions; required manual key entry) |
| Current status | Legacy - modern Avast (One / Premium Security) uses account-based activation |
| Known magic bytes | None publicly documented; identified by file association with Avast |
| Released | 2000s, with commercial (paid) editions of avast! antivirus |
| Latest version | Largely legacy - modern Avast activates via account/subscription, not .avastlic files |
AVASTLIC conversions
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