Dropbox looks to be aiming at convincing users of its business service to upgrade to a paid plan by limiting its app to being downloaded on a maximum of three devices.

The company has imposed the limit only for free account users, while those with Professional and Plus accounts can continue to install it on as many devices as they wish.

People who already have their Dropbox account up and running on more than three devices are apparently still able to access the service across all linked computers, phones and tablets. But the rule came into force for anyone trying to go above the three device threshold from the beginning of March.

So if you have a free account with three or more devices already connected, you’ll be invited to either unlink one device or upgrade (with a free 30-day trial) to a premium service.

It’s worth noting that this is potentially a move by Dropbox to push heavy users of its free service into adopting its professional and business grade tiers.

Although it might upset some personal users, it demonstrates the company’s efforts to try and become more of a premium, enterprise-focussed product.

For individuals, it will remain to be merely a way of storing files, while new collaboration-focused features, such as in-app document editing and note making are better suited to businesses.

Although Dropbox has an estimated 500 million users worldwide, only around 2.5% of those are paying users. Following the company’s move to become a publicly listed company, it needs to start generating revenue for its shareholders.

Upgrading free accounts to paid accounts is a priority, offering those splashing the cash enhanced storage limits as well as the ability to use the app across as many devices as they like.